·       Arrays – Used to process a collection of data all of which is of the same type.

o      Declaration Examples

 

const int NUMBER_OF_EMPLOYEES = 150;

 

int employees[NUMBER_OF_EMPLOYEES];

int students[25];

double numbers[] = {5.6, 2.56, 3.14, 6};

char firstName[] = {‘J’, ‘o’, ‘e’, ‘\0’};

char lastName[] = “Russell”;

 

o      Usage Examples

 

cout << "The first letter in my name is " << firstName[0] << endl;

cout << "My name is " << firstName << " " << lastName << endl;

 

cout << "Enter new last name: ";

cin >> lastName;

firstName[0] = 'M';

 

cout << "My name is " << firstName << " " << lastName << endl;

 

// Good output

 

 

// Bad output due to overstepping the bounds of the “lastName” array

 

o      Arrays In Functions

§       Function Prototype Example

 

int processNumbers(int numbers[]);

int findGridLocation(int gridLocations[][100]);

 

§       Example for passing an entire array to a function.

 

const int NUMBER_OF_STUDENTS = 25;

int grades[NUMBER_OF_STUDENTS];

 

// Code for filling in the student grades goes here

 

// Here is the prototype to calculate the average

double average(const int grades[], const int totalGrades);

 

//  Note:  Use const to make sure that there are no

// changes made to the grades array or totalGrades.

 

// Call the function as follows

double classAverage;

classAverage = average(grades, NUMBER_OF_STUDENTS);

 

o      Multidimensional Arrays – Arrays of more than one dimension

§       A Two Dimensional Array can be thought of as an array of arrays.  The same logic can be applied for arrays of higher dimension.

 

// Declaration Examples

 

      int numbers[3][4]; // Three rows by four columns

      int someMatrix[][3] = { {1, 2, 3},

                                                      {4, 5, 6},

                                                      {7, 8, 9} };

      char somePlaces[][50] = {        "Boston, Massachusetts",

                                                      "Albany, New York",

                                                      "Denver, Colorado"};

 

// Usage Examples

     

      for(int i = 0; i < 3; i++)

      {

                  for(int j = 0; j < 3; j++)

                              cout      << "someMatrix[" << i << "][" << j <<"] is "

                                          << someMatrix[i][j] << endl;

      }

     

      for(int k = 0; k < 3; k++)

                  cout << "The location is " << somePlaces[k] << endl;

 

// Good output

 

·       Strings – Supports the C Programming way of representing strings and a C++ programming string handling facility.

o      We call an array of characters a C-string variable and an array of characters terminated by NULL a C-string

o      The NULL character in a C-string is used to determine the actual ending of the string.  The NULL character does not get counted when determining the length of a C-string

o      Some useful <ctype> predefined C-string functions:

 

 

o      C-string Input / Output

 

// A basic example of C-string I/O:

#include <iostream>

#include <cstring>

using namespace std;

 

int main()

{

char s1[80], s2[80];

cout << “Enter some words: ”;

cin >> s1 >> s2;

cout << “You entered ” << s1 << s2 << endl;

 

return 0;

}

 

Good output and good input (Note: the white space is stripped from the output)

 

Good output, but bad input (Note: the input was more than the program expected.  What happened to “You?”?)

 

// Example that gets a whole line (getline() member function)

#include <iostream>

#include <cstring>

using namespace std;

 

int main()

{

char s[80];

cout << “Enter some words: ”;

cin.getline(s, 80); // Note: the maximum # characters is 79 due to NULL

cout << “You entered ” << s << endl;

 

return 0;

}

 

Good output:

 

// Other member functions useful for C-string I/O

 

 

// Some useful Character-Manipulation Functions.  Note:

// you must include the <cctype> library functions.

 

           

 

·       The Standard Class string – Allows the programmer to treat strings as a basic data type without needing to worry about implementation details.

o      Overloaded operators can be used for assigning and concatenating strings.

o      Default constructor initializes empty string.  A second constructor takes a C-string argument in the declaration.

 

#include <iostream>

#include <string>

using namespace std;

 

int main()

{
      string s1, s2(“Hello World.  ”), s3 = “How are you?”, s4(s2);

 

      s1 = s2 + s3;

 

      cout << “String 1 = ” << s1 << endl;

      cout << “String 2 = ” << s2 << endl;

      cout << “String 3 = ” << s3 << endl;

      cout << “String 4 = ” << s4 << endl;

 

      return 0;

}

 

// The output is shown below

 

o      The string objects do not include the NULL character with the text of the string as is done with a C-string variable.  The string class member functions allow you to use C-string variables, but be aware that there are differences.

 

// This is legal because the memory is dynamically allocated within the object.

string s1;

s1 = “Hello World”;

 

// This is also legal.

char s2[80] = “Hello World”;

 

// This is NOT legal because s3 cannot point to anything other than the

// character array s3.  You must use strcpy() function  to set s3 in this example.

char s3[80];

s3 = “Hello World”;

 

// Note:  The object s1 does not have a NULL character after the ‘d’ in world,

// but the C-string s2 does have a NULL character after the ‘d’ in world.

 

// More Examples:

      string s4(“Have a nice day.”);

      char s5[80];

     

s5 = s4;                        // NOT legal

      strcpy(s5, s4);              // NOT legal

      strcpy(s5, s4.c_str());   // Legal

 

o      Input / Output with the class string

§       The Insertion Operator will display string objects just as any other data types.

 

// Example

      string courseName(“This is C++ Programming.”);

      cout << courseName << endl;

 

§       The extraction Operator will get whitespace- delimited strings and put into string objects.  It will also ignore any leading whitespace.

// Example

      string firstName;

      cout << “What is your first name?  ”;

      cin >> firstName;

      cout << “Hello ” << firstName << endl;

 

§       To get an entire line of input and put into a string object, use the getline() function.  Notice that it is used differently for string objects than it was used for C-strings.

// Example

      string fullName;

      cout << “What is your full name?  ”;

      getline(cin, fullName);

      cout << “Hello ” << fullName << endl;

 

·       Useful Member Functions of the Standard Class string