Tricky C/C++/JAVA/.NET Questions

1)[C] Which is efficient? (a) or (b)

a) main(){

int i,j;

for(i=0;i<=100;i++)

    for(j=0;j<=500;j++)

        printf("%d %d",i,j);

}

 b) main(){

int i,j;

for(j=0;j<=500;j++)

    for(i=0;i<=100;i++)

        printf("%d %d",i,j);

}

Ans: the light-weighted inner loop is efficient,generally. Since the second snippet has the less inner loop iterations less than the outside loop, it is more efficient than the first one.
2)[C]What's the output?

#define sqr(x) (x * x)

main()

{

int i=2,r;

r=sqr(i+3);

printf("%d",r);

}

Ans: 11. Surprising? 'i' in the sqr(i+3) is replaced with 2 and this macro is expanded as 2+3 * 2+3.But not 5 * 5. As the * has the highest priority, it becomes 2+6+3 = 11. Gopalakrishnan.P, Thiagaraja Engineering College, Madurai
3. [C++] #include <iostream.h>

main() {

int i=0;

if(i = = 0) cout<<"i="<<i;

}

Ans.i=0. Because the (i = = 0) is true and thus it becomes if(1). It leads i=0 to get printed. Karthikeyan
4. [C++] #include <iostream.h>

main() {

int i=0;

if(i = 0) cout<<"i="<<i;

}

Ans. No output.= is the assignment operator. In if(i=0), the value 0 is assigned to i and it becomes if(0). Now it searches for an 'else' part. Since it was not there, there would be no output. Pazhamalai Nathan.G
5.[C]

#include
#define ABC 20
#define XYZ 10
#define XXX ABC - XYZ

void main()
{
int a;

a = XXX * 10;
printf("%d\n", a);
}

Ans.a = xxx * 10
which is => a = ABC - XYZ * 10
=> a = 20 - 10 * 10
=> a = 20 - 100
=> a = -80.       Rebecca David, Final-CSE,Easwari Engineering College.
6.[C]

#include
void main()
{
int a, b, c, abc = 0;
a = b = c = 40;

if (c) {
int abc;
abc = a*b+c;
}
printf ("c = %d, abc = %d\n", c, abc);
}

Ans. the result will be c = 40 and abc = 0;
because the scope of the variable 'abc' inside if(c) {.. }
is not valid out side that if (.) { .. }. Rebecca David, Final-CSE,Easwari Engineering College.
7. [C]

#include <stdio.h>

main(){

if(printf(""))

printf("True");

else

printf("False");

}

Ans: printf() function will return an integer that is number of characters printed by that printf function. Here inside the condition no character is printed ( "" ). so, the condition becomes false. The output will be "False"

You can add some more tricky questions and its answers through email.Subject of the email with the prefix:(TQS). Email-id: [email protected]

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