MODULE 2

PROGRAM STRUCTURE

AND BASIC DATA TYPES

 

My Training Period: hours

 

Note:

ANSI C refers to ISO/IEC C.

 

Abilities

 

▪          Able to understand the basic structure of the C/C++ program.

▪          Able to understand and use the basic data types.

▪          Able to recognize and use the keywords and variables.

▪          Able to understand and use the constant, character and escape sequence.

▪          Able to understand and use the C typecasting/promotion.

 

2.1    A Program

 

-              C/C++ programs consist of functions, one of which must be main().  Every C/C++ program begins execution at the main() function.

 

2.2    Program Keywords / Reserved Words

 

-              The keywords used in C/C++ have special meaning to the compiler.  The programmer can’t use these words for identifiers such as variable names.

-              The following table is a list of keywords used in ANSI C.

 

 

-              The following table is a list of C++ keywords; most of the keywords will be used in part II and III of this Tutorial.

 

 

-              One way to master C/C++ programming is to master the keywords and usages☺.

 

2.3    Identifiers

 

-              Simply references to memory locations, which can hold values (data).

-              Are formed by combining letters (both upper and lowercase), digits (0–9) and underscore ( _ ).

-              Rules for identifier naming are:

 

1.         The first character of an identifier must be a letter, an underscore ( _ ) also counts as a letter.

2.         The blank or white space character is not permitted in an identifier.

3.         Can be any length.  Internal identifier (do not have the external linkage) such as preprocessor macro names at least the first 31 characters are significant, also implementation dependent.

4.         Reserved words/keywords and characters such as main and # also cannot be used.

 

2.4      Variables

 

-              Identifier that value may change during the program execution.

-              Every variable stored in the computer’s memory has a name, a value and a type.

-              All variable in a C/C++ program must be declared before they can be used in the program.

-              A variable name in C/C++ is any valid identifier, and must obey the rules mentioned above.

-              Initializing a variable means, give a value to the variable, that is the variable’s initial value and can be changed later on.

-              Variable name are said to be lvalue (left value) because they can be used on the left side of an assignment operator.

-              Constant are said to be rvalue (right value) because they only can be used on the right side of an assignment operator.  For example:

 

x = 20;

x is lvalue, 20 is rvalue.

 

-              Note that lvalue can also be used as rvalue, but not vice versa.

 

Example of the variable declaration

 

int          x, y, z;   

short        number_one;

long         Type0fCar;

unsigned int positive_number;

char         Title;

float        commission, yield;

 

 

Declaring and initializing variables examples:

 

int     m, n = 10;

char * ptr = "TESTING";

float   total, rate = 0.5;

char    user_response = ‘n’;

char    color[7] = "green";

 

Or declare and then initialize:

 

int     m, n;

float   total, rate;

char    user_response;

char    color[7];

 

n = 20;

rate = 4.5;

user_response = ‘n’;

color = "green";

 

2.5     Basic Data types

 

-              Why we need to learn data types?  Every variable used in program hold data, and every data must have their own type.   It is the way how we can ‘measure’ the variable’s data value as exist in the real world.  Further more by knowing the data range, we can use data efficiently in our program in term of memory management (storage allocation) aspects. 

-              For example, no need for us to reserve a lot of storage space such as a long data type if we just want to store a small amount of data, let say, int data type.

-              Every data in C/C++ has their own type.  There are basic data type and derived data type.  This Module deals with basic data type.

-              There are two kinds of basic data type: integral (integer value) and floating (real number).  char data type classified in integral type.

-              Derived data types will be presented in another Module.  Derived data type including the aggregate data type is constructed from basic data type such as arrays, functions, pointers, structures, unions and other user defined data types.  Basic data type and their variation are shown in Table 2.3. 2.4 and 2.5. 

 

 

-              The following tables list the sizes and resulting ranges of the data types based on IBM PC compatible system.  For 64 bits, the size and range may not valid anymore☺.

 

 

 

 

-              We are very familiar with integer constants that are the base 10 numbers, 0 – 9.  There are other bases such as 16, 8 and 2 numbers that we will encounter when learning programming.

-              Octal integer constants must start with 0 followed by any combination of digits taken from 0 through 7.  For examples:

 

0     07   0713 ←represent octal numbers

 

-              Hexadecimal integer constants must start with 0x or 0X (capital hexadecimal) followed by any combination of digits taken from 0 through 9 and uppercase letters A through F.  For examples:

 

                                      0x   0x8  0XADC     0X2FD ←represent hexadecimal numbers

 

-              The literal data-type qualifiers bring different means for same constant data.  For example:

 

§         75 mean the integer 75, but 75L represents the long integer 75.

§         75U means the unsigned integer 75.

§         75UL means the unsigned long integer 75.

§         4.12345 mean the double value 4.12345, but 4.12345F represents the float value 4.12345.

 

2.6     Escape Sequence

 

-              The backslash (\) is called an escape character.  When the backslash is encountered, function such as printf() for example, will look ahead at the next character and combines it with the backslash to form an escape sequence, used in functions printf() and scanf().

-              Table 2.6 is the list of the escape sequence.

 

 

-              For general C++ escape sequences are given in the following table.  Besides using the sequence, we also can use their value representation (in hexadecimal) for example \0x0A for newline.

 

 

2.7    Constants

 

-              Values that do not change during program execution.

-              Can be integer, character or floating point type.

-              To declare a constant, use keyword const as shown in the following variable declaration example:

 

const  int   day_in_week = 7;

const  float   total_loan  =  1100000.35;

 

2.8    Character and String Constants

 

-              A character constant is any character enclosed between two single quotation marks (' and ').

-              When several characters are enclosed between two double quotation marks (" and "), it is called a string.

-              Examples:

 

Character constants:

 

'$'  '*'  ' '  'z'  'P'

 

String constants, note that the blank space(s) considered as string:

 

"Name:   "

"Type of Fruit"

"Day:  "

    "   "

 

-              You will learn other aggregate or derived data type specifiers such as struct, union, enum and typedef in other Modules or in the program examples.

 

2.9    C Typecasting and Type Promotion

 

-              During the program development, you may encounter the situations where you need to convert to the different data type from previously declared variables, as well as having mixed data type in one expression.

-              For example, let say you have declared the following variables:

 

int total, number;

float average;

 

-              But in the middle of your program you encountered the following expression:

 

average = total / number;

 

-              This expression has mixed data type, int and float.  The value of the average will be truncated, and it is not accurate anymore.   Many compilers will generate warning and some do not, but the output will be inaccurate.

-              C provides the unary (take one operand only) typecast operator to accomplish this task.  The previous expression can be re written as

 

average =  (float) total / number;

 

-              This (float) is called type cast operator, which create temporary floating-point copy of the total operand.  The construct for this typecast operator is formed by placing parentheses around a data type name as:

 

(type) such as  (int), (float) and (char).

 

-              In an expression containing the data types int and float for example, the ANSI C standard specifies that copies of int operands are made and promoted to float. 

-              The cast operator normally used together with the conversion specifiers heavily used with printf() and scanf().  C’s type promotion rules specify how types can be converted to other types without losing the data accuracy. 

-              The promotion rules automatically apply to expressions containing values of two or more different data type in mixed type expression.  The type of each value in a mixed-type expression is automatically promoted to the highest type in the expression.

-              Implicitly, actually, only a temporary version of each new value (type) is created and used for the mixed-type expression, the original value with original type still remain unchanged.

-              Table 2.8 list the data types in order from highest to lowest type with printf and scanf conversion specifications for type promotion

-              From the same table, type demotion, the reverse of type promotion is from lowest to highest.  Type demotion will result inaccurate value such as truncated value.  Program examples for this section are presented in formatted file input/output Module.

-              This issue is very important aspect to be taken care when developing program that use mathematical expressions as well as when passing argument values to functions.

-              C++ has some more advanced features for typecasting and will be discussed in Typecasting Module.

 

 

-              A length modifier is listed in the following table.

 

 

-              The following table is a list of the ANSI C formatted output conversion of the printf() function, used with %.  The program examples are presented in Module 5.

 

 

-              The following table is a list of ANSI C formatted input conversion of the scanf() function.

 

 

Program Examples And Experiments

 

Example #1

 

//Data types program example

#include <iostream.h>

#include <stdlib.h>

 

int main()                     //main( ) function

{

    int        a = 3000;  //positive integer data type

    float      b = 4.5345;     //float data type

    char       c = 'A';   //char data type

    long       d = 31456; //long positive integer data type

    long       e = -31456;     //long -ve integer data type

    int       f =  -145; //-ve integer data type

    short      g = 120;   //short +ve integer data type

    short      h = -120;  //short -ve integer data type

    double     i = 5.1234567890;     //double float data type

    float      j = -3.24; //float data type

 

cout<<"Welcome Ladies and Gentlemen!!\n";

cout<<"Here are the list of the C/C++ data type\n";

cout<<"\n1.  This is positive integer number (int):\t\t"<<a;

cout<<"\n2.  This is positive float number (float):\t\t"<<b;

cout<<"\n3.  This is negative float number(float):\t\t"<<j;

cout<<"\n4.  This is character data (char):\t\t\t"<<c;

cout<<"\n5.  This is long positive integer number(long):\t\t"<<d;

cout<<"\n6.  This is long negative integer number(long):\t\t"<<e;

cout<<"\n7.  This is negative integer number(int):\t\t"<<f;

cout<<"\n8.  This is short positive integer number(short):\t"<<g;

cout<<"\n9.  This is short negative integer number(short):\t"<<h;

cout<<"\n10.  This is double positive float number(double):\t"<<i;

cout<<"\n11.\'This is lateral string\'";

cout<<"\n\t---do you understand?----\n ";

system("pause");

return 0;

}

 

Output:

 

 

Example #2

 

//Another data type program example

#include <iostream.h>

#include <stdlib.h>

 

 

void main()         //main( ) function

{

   int              p = 2000;  //positive integer data type

   short int        q = -120;      //variation

   unsigned short int r = 121;       //variation

   float       s = 21.566578; //float data type

   char             t = 'r';   //char data type

   long             u = 5678;  //long positive integer data type

   unsigned long    v = 5678;      //variation

   long             w = -5678; //-ve long integer data type

   int              x =  -171; //-ve integer data type

   short       y = -71;   //short -ve integer data type

   unsigned short   z = 99;    //variation

   double           a = 88.12345;  //double float data type

   float       b = -3.245823;  //float data type

 

cout<<"\t--Data type again--\n";

cout<<"\t-------------------\n";

cout<<"\n1.   \"int\" sample: \t\t"<<p;

cout<<"\n2.   \"short\" int sample: \t"<<q;

cout<<"\n3.   \"unsigned short int\" sample: "<<r;

cout<<"\n4.   \"float\" sample: \t\t"<<s;

cout<<"\n5.   \"char\" sample: \t\t"<<t;

cout<<"\n6.   \"long\" sample: \t\t"<<u;

cout<<"\n7.   \"unsigned long\" sample: \t"<<v;

cout<<"\n8.   negative \"long\" sample: \t"<<w;

cout<<"\n9.   negative \"int\" sample: \t"<<x;

cout<<"\n10.  negative \"short\" sample: \t"<<y;

cout<<"\n11.  unsigned \"short\" sample: \t"<<z;

cout<<"\n12.  \"double\" sample: \t\t"<<a;

cout<<"\n13.  negative \"float\" sample: \t"<<b<<endl;

system("pause");

}

 

Output:

 

 

Example#3

 

//Program to calculate the circumference and area of circle

#include <iostream.h>

#include <stdlib.h>

//define identifier PI with constant

#define  PI   3.14159   

//define identifier TWO with constant

#define  TWO  2.0    

 

int main( )

{

    float   area, circumference, radius;

 

    cout<<"\nEnter the radius of the circle in meter: ";

    cin>>radius;

 

    area = PI * radius * radius;

    //circle area =  PI*radius*radius

   

    circumference = TWO * PI * radius;

    //circumference = 2*PI*radius

    cout<<"\nCircumference = "<<circumference<<" meter";

    //circle circumference

    cout<<"\nCircle area =  "<<area<<" square meter"<<endl;

    //circle area

    system("pause");

    return 0;

 }

 

Output:

 

 

Example #4

 

//Using cout from iostream.h header file

#include <iostream.h>

#include <stdlib.h>

int main()

{

  cout<<"Hello there.\n";

  cout<<"Here is 7: "<<7<<"\n";

  //other than escape sequence \n used for new line, endl...

  cout<<"\nThe manipulator endl writes a new line to the screen.\n"<<endl;

  cout<<"Here is a very big number:\t" << 10000 << endl;

  cout<<"Here is the sum of 10 and 5:\t" << (10+5) << endl;

  cout<<"Here's a fraction number:\t" << (float) 7/12 << endl;

  //simple type casting, from int to float

  cout<<"And a very very big number:\t" << (double) 7000 * 7000<< endl;

  //another type casting, from int to double

  cout<<"\nDon't forget to replace existing words with yours...\n";

  cout<<"I want to be a programmer!\n";

  system("pause");

  return 0;

}

 

Output:

 

 

Example #5

 

//Comment in C/C++, using /*  */ or //

//the // only for C++ compiler

#include <iostream.h>

#include <stdlib.h>

 

int main()

{

  /* this is a comment

  and it extends until the closing

  star-slash comment mark */

  cout<<"Hello World! How are you?\n";

  //this comment ends at the end of the line

  //so, new comment line need new double forward slash

  cout<<"That is the comment in C/C++ program!\n";

  cout<<"They are ignored by compiler!\n";

  //double slash comments can be alone on a line

  /* so can slash-star comments */

  /********************************/

  system("pause");

  return 0;

}

 

Output:

 

 

Example #6

 

//By using predefined sizeof() function,

//displaying the data type size, 1 byte = 8 bits

#include <iostream.h>

#include <stdlib.h>

int main()

{

  cout<<"The size of an int is:\t\t"<<sizeof(int)<<" bytes.\n";

  cout<<"The size of a short int is:\t"<<sizeof(short)<<" bytes.\n";

  cout<<"The size of a long int is:\t"<<sizeof(long)<<" bytes.\n";

  cout<<"The size of a char is:\t\t"<<sizeof(char)<<" bytes.\n";

  cout<<"The size of a float is:\t\t"<<sizeof(float)<<" bytes.\n";

  cout<<"The size of a double is:\t"<<sizeof(double)<<" bytes.\n";

  cout<<"The size of a bool is:\t\t"<<sizeof(bool)<<" bytes.\n";

  system("pause");

  return 0;

}

 

Output:

 

 

Example #7

 

//Demonstration the use of variables

#include <iostream.h>

#include <stdlib.h>

int main()

{

     unsigned short int   Width = 7, Length;

     Length = 10;

     //create an unsigned short and initialize with result

     //of multiplying Width by Length

     unsigned short int Area  = Width * Length;

     cout<<"Width:\t"<<Width<<"\n";

     cout<<"Length: "<<Length<<endl;

     cout<<"Area: \t"<<Area<<endl;

     system("pause");

     return 0;

}

 

Output:

 

 

Example #8

 

//To calculate the total amount of money earned in n days

#include <iostream.h>

#include <stdlib.h>

 

int main( )

{

  int  n;

  int  total, rate= 20;

 

  cout<<"Enter number of days worked:  ";

  cin>>n;

  total = n * rate;

  cout<<"\n----------------------------";

  cout<<"\n|   For rate RM20 per day   |";

  cout<<"\n----------------------------";

  cout<<"\n";

  cout<<"\nFor "<<n<<" days of work, you have earned $ ";

  cout<<total<<endl;

  system("pause");

  return 0;

}

 

Output:

 

 

Example #9

 

//Printing characters base on their

//respective integer numbers

#include <iostream.h>

#include <stdlib.h>

int main()

{

         cout<<"For integer number from 32 till 127,\n";

         cout<<"their representation for\n";

         cout<<"characters is shown below\n\n";

         cout<<"integer     character\n";

         cout<<"-------------------\n";

         for (int i = 32; i<128; i++)

         //display up to 127...

         cout<<i<<"    "<<(char) i<<"\n";

         //simple typecasting, from int to char

         system("pause");

         return 0;

}

 

Output:

 

 

-            Boolean, bool is a lateral true or false.  Use bool and the literals false and true to make Boolean logic tests.

-            The bool keyword represents a type that can take only the value false or true. The keywords false and true are Boolean literals with predefined values. false is numerically zero and true is numerically one. These Boolean literals are rvalues (right value); you cannot make an assignment to them.

-            Program example:

 

/*Sample Boolean tests with bool, true, and false.*/

#include <iostream.h>

#include <stdlib.h>

//non main function

bool func()

{

     //Function returns a bool type

     return NULL;

     //NULL is converted to Boolean false, same

     //as statement 'return false;'

}

int main()

{

     bool val = false;  // Boolean variable

     int i = 1;         // i is neither Boolean-true nor Boolean-false

     int g = 5;

     float j = 3.02;    // j is neither Boolean-true nor Boolean-false

     cout<<"Given the test value: "<<endl;

     cout<<"bool val = false "<<endl;

     cout<<"int i = 1 "<<endl;

     cout<<"int g = 5 "<<endl;

     cout<<"float j = 3.02 "<<endl;

     cout<<"\nTESTING\n";

     //Tests on integers

     if(i == true)

cout<<"True: value i is 1"<<endl;

     if(i == false) 

cout<<"False: value i is 0"<<endl;

     if(g)

cout << "g is true."<<endl;

     else

cout << "g is false."<<endl;

     //To test j's truth value, cast it to bool type.

     if(bool(j) == true)

cout<<"Boolean j is true."<<endl;

     //Test Boolean function returns value

     val = func();

     if(val == false)

cout<<"func() returned false."<<endl;

     if(val == true)

cout<<"func() returned true."<<endl;

     system("pause");

     return false;

     //false is converted to 0

}

 

Output:

 

 

Example #10

 

//Testing the escape sequences

#include <stdio.h>

#include <stdlib.h>

int main()

{

printf("Testing the escape sequences:\n");

printf("-----------------------------\n");

printf("The audible bell  --->\'\\a\' \a\a\a\n");

printf("The backspace     --->\'\\b\' \bTesting\n");

printf("The formfeed, printer      --->\'\\f\' \fTest\n");

printf("The newline       --->\'\\n\' \n\n");

printf("The carriage return        --->\'\\r\' \rTesting\n");

printf("The horizontal tab         --->\'\\t\' \tTesting\t\n");

printf("The vertical tab  --->\'\v\' \vTesting\n");

printf("The backslash              --->\'\\\\' \\Testing\\\n");

printf("The single quote  --->\'\'\'  \'Testing\'\'\'\n");

printf("The double quote  --->\'\"\'  \"Testing\"\"\n");

printf("The question mark --->\'\?\'  \?Testing\?\n");

printf("Some might not working isn't it?\n");

system("pause");

return 0;

}

 

Output:

 

 

Example #11

 

#include <stdio.h>

#include <stdlib.h>

int main()

{

int num;

printf("Conversion...\n");

printf("Start with any character and\n");

printf("Press Enter, EOF to stop\n");

num = getchar();

printf("Character Integer Hexadecimal Octal\n");

while(getchar() != EOF)

{

printf("   %c       %d       %x       %o\n", num, num, num, num);

++num;

}

system("pause");

return 0;

}

 

Output:

 

 

Example #12

 

#include <stdio.h>

#include <stdlib.h>

 

/*convert decimal to binary function*/

void dectobin();

          

int main()

{

char chs = 'Y';

do

{

dectobin();

printf("Again? Y, others to exit: ");

chs = getchar();

scanf("%c", &chs);

}while ((chs == 'Y') || (chs == 'y'));

return 0;

}

 

void dectobin()

{

int input;

printf("Enter decimal number: ");

scanf("%d", &input);

if (input < 0)

printf("Enter unsigned decimal!\n");

 

/*for the mod result*/

int i;

/*count the binary digits*/

int count = 0;

/*storage*/

int binbuff[64];

do

{

/* Modulus 2 to get the remainder of 1 or 0*/

i = input%2;

/* store the element into the array */

binbuff[count] = i;

/* Divide the input by 2 for binary decrement*/

input = input/2;

/* Count the number of binary digit*/

count++;

/*repeat*/

}while (input > 0);

/*prints the binary digits*/

printf ("The binary representation is: ");

do

{

printf("%d", binbuff[count - 1]);

count--;

if(count == 8)

printf(" ");

} while (count > 0);

printf ("\n");

}

 

Output:

 

 

Example #13

 

#include <stdio.h>

#include <stdlib.h>

/*for strlen*/

#include <string.h>

 

/*convert bin to decimal*/

void bintodec()

{

char buffbin[100];

char *bin;

int i=0;

int dec = 0;

int bcount;

 

printf("Please enter the binary digits, 0 or/and 1.\n");

printf("Your binary digits: ");

bin = gets(buffbin);

 

i=strlen(bin);

for (bcount=0; bcount<i; ++bcount)

/*if bin[bcount] is equal to 1, then 1 else 0 */

dec=dec*2+(bin[bcount]=='1'? 1:0);

printf("\n");

printf("The decimal value of %s is %d\n", bin, dec);

}

 

int main(void)

{

bintodec();

return 0;

}

 

Output:

 

 

Example #14

 

/*Playing with binary, decimal, hexadecimal

and octal conversion*/

#include <stdio.h>

#include <stdlib.h>

/*strlen*/

#include <string.h>

 

/*octal conversion function*/

void octal(char *octa, int *octares);

/*hexadecimal conversion function */

void hexadecimal(char *hexa, int *hexares);

/*decimal conversion function */

void decimal(char *deci, int *decires);

 

/*convert binary to decimal*/

void bintodec(void);      

/* convert decimal to binary*/

void decnumtobin (int *dec);         

int main()

{   

/* Yes or No value to continue with program */

char go;

/* Yes or No value to proceed to Binary to Decimal function */

char binY;

 

char choice1;

char choice2;

/* numtest, value to test with, and pass to functions*/

int numtest;

/* value to convert to binary, and call decnumtobin function*/

int bintest;

 

int flag;

flag = 0;

go = 'y';

do

{

printf("Enter the base of ur input(d=dec, h=hex, o=octal): ");

scanf("%c", &choice1);

getchar();

printf("\n");

printf("The entered Number: ");

/*If decimal number*/

if ((choice1 == 'd') || (choice1 == 'D'))

{

scanf("%d", &numtest);

getchar();

}

/*If hexadecimal number*/

else if ((choice1 == 'h') || (choice1 == 'H'))

{

scanf("%x", &numtest);

getchar();

}

/*If octal number*/

else if ((choice1 == 'o') || (choice1 == 'O'))

{

scanf("%o", &numtest);

getchar();

}

/*If no match*/

else

{

flag = 1;

printf("Only d, h or o options!\n");

printf("Program exit...\n");

exit(0);

}

 

/*Firstly convert the input 'number' to binary*/

bintest = numtest;

decnumtobin(&bintest);

 

/*output the hex, decimal or octal*/

printf("\n");

printf("Next, enter the base of ur output (d=dec, h=hex, o=octal): ");

scanf("%c", &choice2);

getchar();

/*If decimal number*/

if ((choice2 == 'd') || (choice2 == 'D'))

decimal (&choice1, &numtest);

/*If hexadecimal number*/

else if ((choice2 == 'h') || (choice2 == 'H'))

hexadecimal (&choice1, &numtest);

/*If octal number*/

else if ((choice2 == 'o') || (choice2 == 'O'))

octal (&choice1, &numtest);

/*if nothing matched*/

else

{

flag = 1;

system("cls");

printf("Only d, h or o options!");

printf("\nProgram exit...");

exit(0);

}

                                                     

printf("\n\nAn OPTION\n");

printf("=========\n");

printf("Do you wish to do the binary to decimal conversion?");

printf("\n Y for Yes, and N for no : ");

scanf("%c", &binY);

getchar();

/*If Yes...*/

if ((binY == 'Y') || (binY == 'y'))

/*Do the binary to decimal conversion*/

bintodec();

/*If not, just exit*/

else if ((binY != 'y') || (binY != 'Y'))

{

flag = 1;

printf("\nProgram exit...\n");

exit(0);

}

 

printf("\n\n");

printf("The program is ready to exit...\n");

printf("Start again? (Y for Yes) : ");

scanf("%c", &go);

getchar();

/*initialize to NULL*/

numtest = '\0';

choice1 = '\0';

choice2 = '\0';

}

while ((go == 'y') || (go == 'Y'));

printf("-----FINISH-----\n");

return 0;

}

 

/*===================================================*/

void decimal(char *deci, int *decires)

{

int ans = *decires;

char ch = *deci;

if ((ch == 'd') || (ch == 'D'))

printf("\nThe number \"%d\" in decimal is equivalent to \"%d\" in decimal.\n", ans, ans);

else if ((ch == 'h') || (ch == 'H'))

printf("\nThe number \"%X\" in hex is equivalent to \"%d\" in decimal.\n", ans, ans);

else if ((ch == 'o') || (ch == 'O'))

printf("\nThe number \"%o\" in octal is equivalent to \"%d\" in decimal.\n", ans, ans);

}

 

/*======================================================*/

void hexadecimal(char *hexa, int *hexares)

{

int ans = *hexares;

char ch = *hexa;

if ((ch == 'd') || (ch == 'D'))

printf("\nThe number \"%d\" in decimal is equivalent to \"%X\" in hexadecimal.\n", ans, ans);

else if ((ch == 'h') || (ch == 'H'))

printf("\nThe number \"%X\" in hex is equivalent to \"%X\" in hexadecimal.\n", ans, ans);

else if ((ch == 'o') || (ch == 'O'))

printf("\nThe number \"%o\" in octal is equivalent to \"%X\" in hexadecimal.\n", ans, ans);

}

 

/*========================================================*/

void octal(char *octa, int *octares)

{

int ans = *octares;

char ch = *octa;

if ((ch == 'd') || (ch == 'D'))

printf ("\nThe number \"%d\" in decimal is equivalent to \"%o\" in octal.\n", ans, ans);

else if ((ch == 'h') || (ch == 'H'))

printf("\nThe number \"%X\" in hex is equivalent to \"%o\" in octal. \n", ans, ans);

else if ((ch == 'o') || (ch == 'O'))

printf("\nThe number \"%o\" in octal is equivalent to \"%o\" in octal.\n", ans, ans);

}

 

void bintodec(void)

{

char buffbin[1024];

char *binary;

int i=0;

int dec = 0;

int z;

printf("Please enter the binary digits, 0 or 1.\n");

printf("Your binary digits: ");

binary = gets(buffbin);

 

i=strlen(binary);

for(z=0; z<i; ++z)

/*if Binary[z] is equal to 1, then 1 else 0 */

dec=dec*2+(binary[z]=='1'? 1:0);

printf("\n");

printf("The decimal value of %s is %d", binary, dec);

printf("\n");

}

 

void decnumtobin (int *dec)

{

int input = *dec;

int i;

int count = 0;

int binary[64];

do

{

/* Modulus 2 to get 1 or a 0*/

i = input%2;

/* Load Elements into the Binary Array */

binary[count] = i;

/* Divide input by 2 for binary decrement */

input = input/2;

/* Count the binary digits*/

count++;

}while (input > 0);

 

/* Reverse and output binary digits */

printf ("The binary representation is: ");

do

{

printf ("%d", binary[count - 1]);

count--;

} while (count > 0);

printf ("\n");

}

 

Output:

 

 

Example #15

 

/*Playing with binary, decimal, hexadecimal

and octal conversion*/

#include <stdio.h>

#include <stdlib.h>

/*strlen*/

#include <string.h>

 

/*decimal conversion function */

void decimal(char *deci, int *decires);

 

/* convert decimal to binary*/

void decnumtobin (int *dec);         

int main()

{   

/* Yes or No value to continue with program */

char go;

 

char choice1;

char choice2;

/*numtest, value to test with, and pass to functions*/

int numtest;

/*value to convert to binary, and call decnumtobin function*/

int bintest;

 

int flag;

flag = 0;

go = 'y';

do

{

printf ("Enter the h for hex input: ");

scanf("%c", &choice1);

getchar();

printf ("\n");

printf ("Enter your hex number lor!: ");

 

/*If hexadecimal number*/

if ((choice1 == 'h') || (choice1 == 'H'))

{

scanf ("%x", &numtest);

getchar();

}

else

{

flag = 1;

printf ("Only h!\n");

printf("Program exit...\n");

exit(0);

}

   

/*Firstly convert the input 'number' to binary*/

bintest = numtest;

decnumtobin(&bintest);

 

/*output the hex, decimal or octal*/

printf ("\n");

printf ("Enter the d for decimal output: ");

scanf ("%c", &choice2);

getchar();

/*If decimal number*/

if ((choice2 == 'd') || (choice2 == 'D'))

decimal(&choice1, &numtest);

/*else...*/

else

{

flag = 1;

printf("Only d!");

printf("\nProgram exit...");

exit(0);

}

 

printf ("\n\n");

printf ("The program is ready to exit...\n");

printf ("Start again? (Y for Yes) : ");

scanf ("%c", &go);

getchar();

/*initialize to NULL*/

numtest = '\0';

choice1 = '\0';

choice2 = '\0';

}

while ((go == 'y') || (go == 'Y'));

printf ("-----FINISH-----\n");

return 0;

}

 

/*===================================================*/

void decimal(char *deci, int *decires)

{

int ans = *decires;

char ch = *deci;

 

if ((ch == 'h') || (ch == 'H'))

printf ("\nThe number \"%X\" in hex is equivalent to \"%d\" in decimal.\n", ans, ans);

}

 

void decnumtobin (int *dec)

{

int input = *dec;

int i;

int count = 0;

int binary[128];

do

{

/* Modulus 2 to get 1 or a 0*/

i = input%2;

/* Load Elements into the Binary Array */

binary[count] = i;

/* Divide input by 2 for binary decrement */

input = input/2;

/* Count the binary digits*/

count++;

}while (input > 0);

 

/* Reverse and output binary digits */

printf ("The binary representation is: ");

do

{

printf ("%d", binary[count - 1]);

count--;

if(count == 4)

printf(" ");

} while (count > 0);

printf ("\n");

}

 

Output:

 

 

Example #16

 

/*Playing with hexadecimal and ascii*/

#include <stdio.h>

#include <stdlib.h>

/*strlen*/

#include <string.h>

 

/*decimal conversion function */

void decimal(int *decires);

/*convert decimal to binary*/

void decnumtobin (int *dec);

 

int main()

{   

/*Program continuation...*/

char go;

 

/* numtest, value to test with, and pass to functions*/

int numtest;

/* value to convert to binary, and call decnumtobin function*/

int bintest;

int flag = 0;

go = 'y';

do

{

printf("Playing with hex and ASCII\n");

printf("==========================\n");

printf("For hex, 0(0) - 1F(32) are non printable/control characters!\n");

printf("For hex > 7F(127) they are extended ASCII characters that are\n");

printf("platform dependent!\n\n");

printf("Enter the hex input: ");

scanf("%x", &numtest);

getchar();

 

/*Firstly convert the input 'number' to binary*/

bintest = numtest;

decnumtobin(&bintest);

 

decimal (&numtest);

printf("\nStart again? (Y for Yes) : ");

scanf ("%c", &go);

getchar();

/*initialize to NULL*/

numtest = '\0';

}

while ((go == 'y') || (go == 'Y'));

printf("-----FINISH-----\n");

return 0;

}

 

/*===================================================*/

void decimal(int *decires)

{

int ans = *decires;

/*If < decimal 32...*/

if(ans < 32)

{

printf("hex < 20(32) equivalent to non printable/control ascii characters\n");

switch(ans)

{

case 0:{printf("hex 0 is NULL ascii");}break;

case 1:{printf("hex 1 is SOH-start of heading ascii");}break;

case 2:{printf("hex 2 is STX-start of text ascii");}break;

case 3:{printf("hex 3 is ETX-end of text ascii");}break;

case 4:{printf("hex 4 is EOT-end of transmission ascii");}break;

case 5:{printf("hex 5 is ENQ-enquiry ascii");}break;

case 6:{printf("hex 6 is ACK-acknowledge ascii");}break;

case 7:{printf("hex 7 is BEL-bell ascii");}break;

case 8:{printf("hex 8 is BS-backspace ascii");}break;

case 9:{printf("hex 9 is TAB-horizontal tab ascii");}break;

case 10:{printf("hex A is LF-NL line feed, new line ascii");}break;

case 11:{printf("hex B is VT-vertical tab ascii");}break;

case 12:{printf("hex C is FF-NP form feed, new page ascii");}break;

case 13:{printf("hex D is CR-carriage return ascii");}break;

case 14:{printf("hex E is SO-shift out ascii");}break;

case 15:{printf("hex F is SI-shift in ascii");}break;

case 16:{printf("hex 10 is DLE-data link escape ascii");}break;

case 17:{printf("hex 11 is DC1-device control 1 ascii");}break;

case 18:{printf("hex 12 is DC2-device control 2 ascii");}break;

case 19:{printf("hex 13 is DC3-device control 3 ascii");}break;

case 20:{printf("hex 14 is DC4-device control 4 ascii");}break;

case 21:{printf("hex 15 is NAK-negative acknowledge ascii");}break;

case 22:{printf("hex 16 is SYN-synchronous idle ascii");}break;

case 23:{printf("hex 17 is ETB-end of trans. block ascii");}break;

case 24:{printf("hex 18 is CAN-cancel ascii");}break;

case 25:{printf("hex 19 is EM-end of medium ascii");}break;

case 26:{printf("hex 1A is SUB-substitute ascii");}break;

case 27:{printf("hex 1B is ESC-escape ascii");}break;

case 28:{printf("hex 1C is FS-file separator ascii");}break;

case 29:{printf("hex 1D is GS-group separator ascii");}break;

case 30:{printf("hex 1E is RS-record separator ascii");}break;

case 31:{printf("hex 1F is US-unit separator ascii");}break;

}

}

else

printf ("\nThe number \"%X\" in hex is equivalent to \"%c\" ascii character.\n", ans, ans);

}

 

void decnumtobin (int *dec)

{

int input = *dec;

int i;

int count = 0;

int binary[128];

do

{

/* Modulus 2 to get 1 or a 0*/

i = input%2;

/* Load Elements into the Binary Array */

binary[count] = i;

/* Divide input by 2 for binary decrement */

input = input/2;

/* Count the binary digits*/

count++;

}while (input > 0);

 

/* Reverse and output binary digits */

printf("The binary representation is: ");

do

{

printf("%d", binary[count - 1]);

count--;

if(count == 4)

printf(" ");

} while (count > 0);

printf("\n");

}

 

Output:

 

 

Example #17

 

-              Compiled using VC++/VC++ .Net.

 

#include <cstdio>

using namespace std;

 

int main()

{

int num;

 

printf("Conversion...\n");

printf("Start with any character and\n");

printf("Press Enter, EOF to stop\n");

num = getchar();

printf("Character Integer Hexadecimal Octal\n");

while(getchar() != EOF)

{

printf("   %c       %d       %x       %o\n", num, num, num, num);

++num;

}

return 0;

}

 

Output:

 

 

-              Program example compiled using gcc.

 

/*Another data type program example*/

#include <stdio.h>

 

/*main function*/

int main()

{

   int                  p = 2000;       /*positive integer data type*/

   short int            q = -120;      /*variation*/

   unsigned short int   r = 121;                /*variation*/

   float                s = 21.566578; /*float data type*/

   char                 t = 'r';        /*char data type*/

   long                 u = 5678;       /*long positive integer data type*/

   unsigned long        v = 5678;      /*variation*/

   long                 w = -5678;      /*-ve long integer data type*/

   int                  x =  -171;      /*-ve integer data type*/

   short                y = -71;        /*short -ve integer data type*/

   unsigned short       z = 99;         /*variation*/

   double               a = 88.12345;  /*double float data type*/

   float                b = -3.245823;  /*float data type*/

 

printf("\t--Data type again--\n");

printf("\t-------------------\n");

printf("\n1.   \"int\" sample: \t\t %d, the data size: %d bytes", p, sizeof(p));

printf("\n2.   \"short\" int sample: \t %d, the data size: %d bytes", q, sizeof(q));

printf("\n3.   \"unsigned short int\" sample: %d, the data size: %d bytes", r, sizeof(r));

printf("\n4.   \"float\" sample: \t\t %.7f, the data size: %d bytes", s, sizeof(s));

printf("\n5.   \"char\" sample: \t\t %c, the data size: %d byte", t, sizeof(t));

printf("\n6.   \"long\" sample: \t\t %d, the data size: %d bytes", u, sizeof(u));

printf("\n7.   \"unsigned long\" sample: \t %d, the data size: %d bytes", v, sizeof(v));

printf("\n8.   negative \"long\" sample: \t %d, the data size: %d bytes", w, sizeof(w));

printf("\n9.   negative \"int\" sample: \t %d, the data size: %d bytes", x, sizeof(x));

printf("\n10.  negative \"short\" sample: \t %d, the data size: %d bytes", y, sizeof(y));

printf("\n11.  unsigned \"short\" sample: \t %d, the data size: %d bytes", z, sizeof(z));

printf("\n12.  \"double\" sample: \t\t %.4f, the data size: %d bytes", a, sizeof(a));

printf("\n13.  negative \"float\" sample: \t %.5f, the data size: %d bytes\n", b, sizeof(b));

return 0;

}

 

[bodo@bakawali ~]$ gcc datatype.c -o datatype

[bodo@bakawali ~]$ ./datatype

 

        --Data type again--

        -------------------

 

1.   "int" sample:               2000, the data size: 4 bytes

2.   "short" int sample:         -120, the data size: 2 bytes

3.   "unsigned short int" sample: 121, the data size: 2 bytes

4.   "float" sample:             21.5665779, the data size: 4 bytes

5.   "char" sample:              r, the data size: 1 byte

6.   "long" sample:              5678, the data size: 4 bytes

7.   "unsigned long" sample:     5678, the data size: 4 bytes

8.   negative "long" sample:     -5678, the data size: 4 bytes

9.   negative "int" sample:      -171, the data size: 4 bytes

10.  negative "short" sample:    -71, the data size: 2 bytes

11.  unsigned "short" sample:    99, the data size: 2 bytes

12.  "double" sample:            88.1235, the data size: 8 bytes

13.  negative "float" sample:    -3.24582, the data size: 4 bytes

 

#include <stdio.h>

#include <stdlib.h>

 

/*convert decimal to binary function*/

void dectobin();

 

int main()

{

char chs = 'Y';

do

{

dectobin();

printf("Again? Y, others to exit: ");

chs = getchar();

scanf("%c", &chs);

}while ((chs == 'Y') || (chs == 'y'));

return 0;

}

 

void dectobin()

{

int input;

printf("Enter decimal number: ");

scanf("%d", &input);

if (input < 0)

printf("Enter unsigned decimal!\n");

 

/*for the mod result*/

int i;

/*count the binary digits*/

int count = 0;

/*storage*/

int binbuff[64];

do

{

/* Modulus 2 to get the remainder of 1 or 0*/

i = input%2;

/* store the element into the array */

binbuff[count] = i;

/* Divide the input by 2 for binary decrement*/

input = input/2;

/* Count the number of binary digit*/

count++;

/*repeat*/

}while (input > 0);

/*prints the binary digits*/

printf("The binary representation is: ");

do

{

printf("%d", binbuff[count - 1]);

count--;

if(count == 8)

printf(" ");

} while (count > 0);

printf ("\n");

}

 

[bodo@bakawali ~]$ gcc binary.c -o binary

[bodo@bakawali ~]$ ./binary

 

Enter decimal number: 64

The binary representation is: 1000000

Again? Y, others to exit: Y

Enter decimal number: 128

The binary representation is: 10000000

Again? Y, others to exit: Y

Enter decimal number: 32

The binary representation is: 100000

Again? Y, others to exit: Y

Enter decimal number: 100

The binary representation is: 1100100

Again? Y, others to exit: N

[bodo@bakawali ~]$ cat binary.c

 

----------------------------------------------------o0o---------------------------------------------------

 

Notes:

The ASCII, EBCDIC and UNICODE character sets reference Table can be found here: http://www.lookuptables.com/