Output of C programs | Set 48

1. What is the output of following program?

#include <stdio.h>
#define square(x) (x * x)

int main()
{
    int x, y = 1;
    x = square(y + 1);
    printf("%d\n", x);
    return 0;
}

Options:
(A) Error
(B) 4
(C) 3
(D) Garbage value

Answer : (C)

Explanation : The macro function square(x)(x*x) calculates the square of the given number.

Initially int y = 1;
In the  next step  x = square(y+1); 
 x = y+1 * y+1; Here square(x) is replaced  x*x .
 x = 1+1 * 1+1; 
 x = 1 + 1 + 1; 
 x = 3; 

2. What is the output of following program?
The code given below is executed from command Line.
Input given by the user: myfile 2 4 6

// myprog.c
#include <stdio.h>

int main(int argc, char* argv[])
{
    int result;
    result = argv[2] + argv[4] + argv[6];
    printf("%d", result);
    return 0;
}

Options:
(A) It will reflect a garbage value.
(B) Error
(C) 12
(D) myfile 12

Answer : (B) Error

Explanation : Error because argv[2], argv[4] and argv[6] areof string type and we cannot perform arithmetic operations without converting the string to integer type.

3. What is the output of following program?

#include <stdio.h>
void main()
{
    unsigned char x = 400;
    printf("%d", x);
}

Options:
(A) Error
(B) 144
(C) 400
(D) Garbage value

Answer :(B) 144 

Explanation : Since the input is beyond the range of unsigned char it will reflect the input’s cyclic value.

4.What is the output of following program?

#include <stdio.h>
int main()
{
    int i;
    char input;
    for (i = 1; i <= 5; i++) {
        // The input provided is 'X'
        scanf("%c", &input);
        printf("%c", input);
        ungetc(input, stdin);
    }
    return 0;
}

Options:
(A) Error
(B) X
(C) XXXXX
(D) A garbage value.

Answer:(C)- XXXXX 

Explanation:The loop will run 5 times. Now, we provide the input as ‘X’. Which is scanned as ‘input’.

printf("%c", input);
The above line prints 'X'

Now the ungetc(input, stdin) statement pushes the character’X’ back into input stream.

For the next run of the loop.
The scanf statement gets the input from “stdin” because of “ungetc” function used previously. Now the printf statement will print ‘X’ Since input= ‘X’ and ungetc(input, stdin) pushes ‘X’ back to the input stream and the same process will take place for the remaining iterations.

5. What is the output of following program?

#include <stdio.h>
int main()
{
    printf("Geeksfor ", "Geeks\n");
    return 0;
}

Options:
(A) Geeksfor
(B) GeeksforGeeks
(C) Error
(D) Geeks

Answer:(A) Geeksfor

Explanation : printf() allows variable number of arguments. Since there is no format specifier, second parameter is ignored with warning.

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