Output of C programs | Set 54

1. What will be the output of the below program?

Options: 
1. 100 
2. compile error 
3. No output 
4. abnormal termination 

The answer is option(1).

Explanation: As GEEKS macro replace the GEEKS with 100 token. 
Refer: https://www.geeksforgeeks.org/interesting-facts-preprocessors-c/

2. What will be the output of the following program?

C++

#include <stdio.h>
#include <string.h>
int main()
{
    printf("%d%d", sizeof("GEEKSFORGEEKS"), strlen("GEEKSFORGEEKS"));
    return (0);
}

Options: 
1. 1314 
2. 1134 
3. 1413 
4. 3114 

 The output is option(3).

Explanation: As we all know that strlen() function return the length without counting \0(null) character but sizeof() function return the length of string with \0 character. 
Refer: https://www.geeksforgeeks.org/difference-strlen-sizeof-string-c-reviewed/

3. Guess the output?  

C++

#include <stdio.h>
int main()
{
    int a = - - 4;
    printf("%d", a);
    return (0);
}

Options: 
1. -4 
2. compile error 
3. runtime error 
4. 4 

The answer is option(4).

Explanation: When we use unary minus(-) operator twice then the compiler treats as plus.

4. What will be the output?

C++

#include <stdio.h>
int main()
{
    char c[] = "GFG";
    int i;
    for (i = 0; c[i]; i++) {
        printf("%c%c%c%c", c[i], *(c + i), *(i + c), i);
    }
    return (0);
}

Output

GGGGFFFFGGGG

Options: 
1. compile time error 
2. GGGFFFGGG 
3. GFG 
4. No output 

 The answer is option(2).

Explanation : Here all c[i], *(c+i), *(i+c), i represent the same thing. In the first loop, all four specifiers points to G that’s why in the first loop it prints GGG and in the 2nd loop FFF and at last in the 3rd loop GGG.

5. What will be the output of following program?

C++

#include <stdio.h>
int main()
{
    int a = 055, b = 55;
    printf("%d%d", a, b);
    return (0);
}

Options: 
1. 4555 
2. 5545 
3. 5545 
4. 5554 

 The answer is option(1).

Explanation: Any integer number which is prefix with 0 indicates as Octal number. Now after the conversion of 055 into decimal number we have 45 and b is 55. Therefore the answer is 4555.