Question 1

What will be the output of the program?

#include<stdio.h>
#include<string.h>

int main()
{
    char dest[] = {97, 97, 0};
    char src[] = "aaa";
    int i;
    if((i = memcmp(dest, src, 2))==0)
        printf("Got it");
    else
        printf("Missed");
    return 0;
}

Answer

Answer: B

memcmp compares the first 2 bytes of the blocks dest and src as unsigned chars. So, the ASCII value of 97 is 'a'.

if((i = memcmp(dest, src, 2))==0) When comparing the array dest and src as unsigned chars, the first 2 bytes are same in both variables.so memcmp returns '0'.
Then, the if(0=0) condition is satisfied. Hence the output is "Got it".

Question 2

What will be the output of the program?

#include<stdio.h>
#include<stdlib.h>

int main()
{
    char *i = "55.555";
    int result1 = 10;
    float result2 = 11.111;
    result1 = result1+atoi(i);
    result2 = result2+atof(i);
    printf("%d, %f", result1, result2);
    return 0;
}

Answer

Answer: C

Function atoi() converts the string to integer.
Function atof() converts the string to float.

result1 = result1+atoi(i);
Here result1 = 10 + atoi(55.555);
result1 = 10 + 55;
result1 = 65;

result2 = result2+atof(i);
Here result2 = 11.111 + atof(55.555);
result2 = 11.111 + 55.555000;
result2 = 66.666000;
So the output is "65, 66.666000" .

Question 3

What will be the output of the program?

#include<stdio.h>

int main()
{
    int i;
    char c;
    for(i=1; i<=5; i++)
    {
        scanf("%c", &c); /* given input is 'b' */
        ungetc(c, stdout);
        printf("%c", c);
        ungetc(c, stdin);
    }
    return 0;
}

Answer

Answer: C

The ungetc() function pushes the character c back onto the named input stream, which must be open for reading.

This character will be returned on the next call to getc or fread for that stream.

One character can be pushed back in all situations.

A second call to ungetc without a call to getc will force the previous character to be forgotten.

Question 4

What will be the output of the program?

#include<stdio.h>

int main()
{
    int i;
    i = scanf("%d %d", &i, &i);
    printf("%d\n", i);
    return 0;
}

Answer

Answer: B

scanf() returns the number of variables to which you are provding the input.

i = scanf("%d %d", &i, &i); Here Scanf() returns 2. So i = 2.

printf("%d\n", i); Here it prints 2.

Question 5

What will be the output of the program?

#include<stdio.h>
#include<math.h>

int main()
{
    float i = 2.5;
    printf("%f, %d", floor(i), ceil(i));
    return 0;
}

Answer

Answer: C

Both ceil() and floor() return the integer found as a double.

floor(2.5) returns the largest integral value(round down) that is not greater than 2.5. So output is 2.000000.

ceil(2.5) returns 3, while converting the double to int it returns '0'.
So, the output is '2.000000, 0'.

Questions for: Library Functions