View source for C Coding Questions ← C Coding Questions

<metadesc>C coding questions for understanding the concepts and features of C language</metadesc>
<quiz display="simple">
{'''1. What is the output of this program?'''
<syntaxhighlight lang="c" >
#include<stdio.h>
int main()
{
    char *ptr;
    char string[] = "How are you?";
    ptr = string;
    ptr += 4;
    printf("%s",ptr);
    return 0;

</syntaxhighlight>
&#125;
}
-'''(a)''' How are you?

+'''(b)''' are you?

-'''(c)''' are

-'''(d)''' No output



{'''2. Which of the following will print the value 2 for the above code?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    int a[10][20][30] = {0};
    a[5][2][1] = 2;

    return 0;
}
</syntaxhighlight>
-'''(a)''' printf("%d",*(((a+5)+2)+1));

-'''(b)''' printf("%d",***((a+5)+2)+1);

+'''(c)''' printf("%d",*(*(*(a+5)+2)+1));

-'''(d)''' None of these


{'''3.  What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    int a = 5;
    int b = ++a * a++;
    printf("%d ",b);
    return 0;
}
</syntaxhighlight>
-'''(a)'''25

-'''(b)''' 30

-'''(c)''' 36

+'''(d)''' Undefined Behavior


{'''4. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    int a = 5;
    switch(a)
    {
        default:
        a = 4;
        case 6:
            a--;
        case 5:
            a = a+1;
        case 1:
            a = a-1;
    }
    printf("%d \n",a);

    return 0;
}
</syntaxhighlight>
+'''(a)''' 5

-'''(b)''' 4

-'''(c)''' 3

-'''(d)''' None of these


{'''5. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    int a = 2,b = 5;
    a = a^b;
    b = b^a;
    printf("%d %d",a,b);

    return 0;
}
</syntaxhighlight>
+'''(a)''' 5 2

-'''(b)''' 2 5

-'''(c)''' 7 7

-'''(d)''' 7 2


{'''6. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include <stdio.h>
int main()
{
    int a[][3] = {1, 2, 3, 4, 5, 6};
    int (*ptr)[3] = a;
    printf("%d %d ", (*ptr)[1], (*ptr)[2]);
    ++ptr;
    printf("%d %d\n", (*ptr)[1], (*ptr)[2]);

    return 0;
}
</syntaxhighlight>
-'''(a)''' 2 3 5 6

+'''(b)''' 2 3 4 5

-'''(c)''' 4 5 0 0

-'''(d)''' none of the above


{'''7. What is the output of the following program? '''
<syntaxhighlight lang="c">
#include <stdio.h>
void f(char**);

int main()
{
    char *argv[] = { "ab", "cd", "ef", "gh", "ij", "kl" };
    f(argv);

    return 0;
}
void f(char **p)
{
    char *t;
    t = (p += sizeof(int))[-1];
    printf("%s\n", t);
}
</syntaxhighlight>
-'''(a)''' ab

-'''(b)''' cd

-'''(c)''' ef

+'''(d)''' gh


{'''8. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include <stdarg.h>
#include <stdio.h>

int ripple(int n, ...)
{
    int i, j, k;
    va_list p;
    k = 0;
    j = 1;
    va_start(p, n);
    for (; j < n; ++j)
    {
        i = va_arg(p, int);
        k += i;
    }
    va_end(p);
    
    return k;
}
int main()
{
    printf("%d\n", ripple(3, 5, 7));

    return 0;
}
</syntaxhighlight>
-'''(a)''' 12

-'''(b)''' 5

+'''(c)''' 7

-'''(d)''' 15


{'''9. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include <stdio.h>
int counter(int i)
{
    static int count = 0;
    count = count + i;
    
    return count;
}
{
int main()
{
    int i, j;
    for (i = 0; i <= 5; i++)
        j = counter(i);
    printf("%d\n", j);

    return 0;
}
</syntaxhighlight>
'''(a)''' 10

'''(b)''' 15

'''(c)''' 6

'''(d)''' 7


{'''10.  What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    const int x = 5;
    const int *ptrx;
    ptrx = &x;
    *ptrx = 10;
    printf("%d\n", x);

    return 0;
}
</syntaxhighlight>
'''(a)''' 5

'''(b)''' 10

'''(c)''' Compile Error

'''(d)''' Garbage value


{'''11. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
#define x 4+1
int main()
{
    int i;
    i = x*x*x;
    printf("%d",i);

    return 0;
}
</syntaxhighlight>
'''(a)''' 125

'''(b)''' 13

'''(c)''' 17

'''(d)''' None of above


{'''12. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    char c=125;
    c=c+10;
    printf("%d",c);

    return 0;
}
</syntaxhighlight>
'''(a)''' 135

'''(b)''' +INF

'''(c)''' -121

'''(d)''' -8


{'''13. What is the output of the following program?'''
<syntaxhighlight lang="c">	 	

#include<stdio.h>
int main()
{
    int i=10;
    static int x=i;
    if(x==i)
        printf("Equal");
    else if(x>i)
        printf("Greater");
    else
        printf("Lesser");

    return 0;
}
</syntaxhighlight>
'''(a)''' Equal

'''(b)''' Greater 

'''(c)''' Lesser 

'''(d)''' Compile Error


{'''14. Consider the following code segment:'''
<syntaxhighlight lang="c">
#include <stdlib.h>

int *f1()
{
    int x = 10;
    return &x;
}
int *f2()
{
    int *ptr;
    *ptr = 10;
    return ptr;
}
int *f3()
{
    int *ptr;
    ptr = (int*) malloc(sizeof (*ptr));
    return ptr;
}
</syntaxhighlight>
'''Which of these functions uses pointers incorrectly?'''

'''(a)''' f3 only

'''(b)''' f1 and f3

'''(c)''' f1 and f2

'''(d)''' f1, f2, and f3


{'''15. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include <stdio.h>
int main()
{
    int i = 3;
    int j;
    j = sizeof(++i + ++i);
    printf("i=%d j=%d\n", i, j);

    return 0;
}
</syntaxhighlight>
-'''(a)''' i=4 j=4

-'''(b)''' i=3 j=4

-'''(c)''' i=5 j=4

+'''(d)''' the behavior is undefined


{'''16. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include <stdio.h>
void f1(int*, int);
void f2(int*, int);
void (*p[2])(int*, int);

int main()
{
    int a = 3;
    int b = 5;
    p[0] = f1;
    p[1] = f2;
    p[0](&a, b);
    printf("%d %d ", a, b);
    p[1](&a, b);
    printf("%d %d\n", a, b);

    return 0;
}

void f1(int *p, int q)
{
    int tmp = *p;
    *p = q;
    q = tmp;
}
void f2(int *p, int q)
{
    int tmp = *p;
    *p = q;
    q = tmp;
}
</syntaxhighlight>
+'''(a)''' 5 5 5 5

-'''(b)''' 3 5 3 5

-'''(c)''' 5 3 3 5

-'''(d)''' none of the above


{'''17. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include <stdio.h>
void e(int);

int main()
{
    int a = 3; 
    e(a);
    putchar('\n');

    return 0;
}
void e(int n)
{
    if (n > 0)
    {
        e(--n);
        printf("%d ", n);
        e(--n);
    }
}
</syntaxhighlight>
+'''(a)'''0 1 2 0

-'''(b)''' 0 1 2 1

-'''(c)''' 1 2 0 1

-'''(d)''' 0 2 1 1


{'''18. Consider the following code segment:'''
<syntaxhighlight lang="c">
typedef int (*test)(float*, float*);
test tmp;
</syntaxhighlight>
'''What is the type of tmp?'''


-'''(a)''' function taking two pointer-to-float arguments and returning pointer to int

-'''(b)''' pointer to int

+'''(c)''' pointer to function taking two pointer-to-float arguments and returning int

-'''(d)''' none of the above


{'''19. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include <stdio.h>

int main()
{
    char p;
    char buf[10] = {1, 2, 3, 4, 5, 6, 9, 8};
    p = (buf + 1)[5];
    printf("%d\n", p);

    return 0;
}
</syntaxhighlight>
-'''(a)''' 5

+'''(b)''' 6

-'''(c)''' 9

-'''(d)''' none of the above


{'''20. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include <stdio.h>
int main()
{
    struct node
    {
        int a;
        int b;
        int c;
    };
    struct node s = { 3, 5, 6 };
    struct node *pt = &s;
    printf("%d\n", *((int*)pt+1));

    return 0;
}
</syntaxhighlight>
-'''(a)''' 3

+'''(b)''' 5

-'''(c)''' 6

-'''(d)''' 7


{'''21. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include <stdio.h>
int main(void)
{
    char a[5] = { 1, 2, 3, 4, 5 };
    char *ptr = (char*)(&a + 1);
    printf("%d %d\n", *(a + 1), *(ptr - 1));

    return 0;
}
</syntaxhighlight>
-'''(a)''' Compile Error

-'''(b)''' 2 1

+'''(c)''' 2 5

-'''(d)''' none of the above


{'''22. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include <stdio.h>
void foo(int[][3]);

int main(void)
{
    int a[3][3] = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} };
    foo(a);
    printf("%d\n", a[2][1]);

    return 0;
}

void foo(int b[][3])
{
    ++b;
    b[1][1] = 9;
}
</syntaxhighlight>
+'''(a)''' 8

-'''(b)''' 9

-'''(c)''' 7

-'''(d)''' none of the above


{'''23. Consider the following function:'''
<syntaxhighlight lang="c">
int foo(int x, int n)
{
    int val = 1;
    if (n > 0)
    {
        if (n % 2 == 1)
        val *= x;
        val *= foo(x * x, n / 2);
    }
    return val;
}
</syntaxhighlight>
'''What function of x and n is computed by foo?'''

+'''(a)''' x^n

-'''(b)''' x×n

-'''(c)''' nx

-'''(d)''' none of the above

{'''24. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>

int main()
{
    int a = 0;
    switch(a)
    {
        default:
            a = 4;
        case 6:
            a--;
        case 5:
            a = a+1;
        case 1:
            a = a-1;
    }
    printf("%d \n",a);

    return 0;
}	
</syntaxhighlight>
-'''(a)''' 5

-'''(b)''' 4

+'''(c)''' 3

-'''(d)''' 0


{'''25. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    int a = 2;
    if(a == (1,2))
        printf("Hello");
    if(a == 1,2)
        printf("World");

    return 0;
}
</syntaxhighlight>
+'''(a)''' Hello

-'''(b)''' World

-'''(c)''' Hello World

-'''(d)''' Compile Error


{'''26. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    int a = 1,2;
    int b = (1,2);
    if(a == b)
        printf("Equal");
    else
        printf("Not Equal");

    return 0;
}
</syntaxhighlight>
-'''(a)''' Equal

+'''(b)''' Not Equal

-'''(c)''' Compiler Dependent

-'''(d)''' Compile Error


{'''27. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
void foo(char *);

int main()
{
    char *string = "Hello";
    foo(string);
    printf("%s",string);

    return 0;
}

void foo(char *a)
{
    while(*a)
    {
        *a += 1;
        a++;
    }
}
</syntaxhighlight>
-'''(a)''' Hello

-'''(b)''' Ifmmp

-'''(c)''' Compile Error

+'''(d)''' Segmentation fault


{'''28. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
#include<stdlib.h>
int main()
{
    char s[] = "Opendays2012";
    int i = 0;
    while(*(s++))
        i++;
    printf("%d",i);

    return 0;
}
</syntaxhighlight>
-'''(a)''' Segmentation Fault

+'''(b)''' Compile Error 

-'''(c)''' 12

-'''(d)''' 0


{'''29. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int a = 10;
int main()
{
    fun();
    fun();

    return 0;
}

int fun()
{
    static int a = 1;
    printf("%d ",a);
    a++;

    return 0;
}
</syntaxhighlight>
+'''(a)''' 1 2

-'''(b)''' 1 1

-'''(c)''' 10 11

-'''(d)''' 10 10


{'''30. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include <stdio.h>
#define crypt(s,t,u,m,p,e,d) m##s##u##t
#define begin crypt(a,n,i,m,a,t,e)
int begin() 
{
    printf("Hello\n");

    return 0;
}
</syntaxhighlight>
+'''(a)''' Hello

-'''(b)''' Link error

-'''(c)''' Segmentation fault

-'''(d)''' Compiler error

</quiz>
'''31. Consider the following program:'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    int a[10][20][30]={0};
    printf("%ld",&a+1 - &a);

    return 0;
}
</syntaxhighlight>
'''What is the output of this program?'''
'''Ans''':


'''32. Consider the following program:'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    int a[10][20][30] = {0};
    int *b = a;
    int *c = a+1;
    printf("%ld", c-b);

    return 0;
}
</syntaxhighlight>
'''What is the output of this program?'''
(You may ignore compiler warnings)

'''Ans''':


'''33. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
#include<stdlib.h>
int* fun();

int main()
{
    int *a = fun();
    printf("%d",*a);

    return 0;
}
int* fun()
{
    int *a =(int*) malloc(sizeof(int));
    *a = 10;
    return a;
}
</syntaxhighlight>

'''Ans''':


'''34. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    int *a = fun();
    printf("%d",*a);

    return 0;
}
int fun()
{
    int a = 10;
    return a;
}
</syntaxhighlight>

'''Ans''':


'''35. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
#include<string.h>

int main()
{
    char string[] = "Hello";
    printf("%lu %lu",sizeof(string),strlen(string));

    return 0;
}
</syntaxhighlight>

'''Ans''':


'''36. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    float a = 0.5;
    if(a == 0.5)
        printf("Yes");
    else
        printf("No");

    return 0;
}
</syntaxhighlight>

'''Ans''':


'''37. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
#include<string.h>
void foo(char *);

int main()
{
    char a[100] = {0};
    printf("%lu %lu",sizeof(a),strlen(a));

    return 0;
}
</syntaxhighlight>

'''Ans''':



	 	 	 	
'''38. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    int a;
    printf("%d",scanf("%d",&a));

    return 0;
}
</syntaxhighlight>


'''Ans''':

'''39. If the binary equivalent of 5.375 in normalised form is 0100 0000 1010 1100 0000
0000 0000 0000, what will be the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
#include<math.h>

int main()
{
    float a=5.375;
    char *p;
    int i;
    p = (char*)&a;
    for(i=0; i<2; i++)
        printf("%02x ", (unsigned char)(p[i]^p[3-i]));

    return 0;
}
</syntaxhighlight>
'''Ans''':


'''40. What is the output of the following program?'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    char str[] = {'a','b','c','\0'};
    str[0] -= 32;
    printf("%s",str);

    return 0;
}
</syntaxhighlight>

'''Ans''':
	

'''41. What is the following function doing?'''
<syntaxhighlight lang="c">
int foo(int n)
{
    int sum = 0;
    while(n > 0)
    {
        n = n & n-1;
        sum++;
    }
    return sum;
}
</syntaxhighlight>
'''Ans''':



'''42. What is the following function doing?'''
<syntaxhighlight lang="c">
int foo(int a, int b)
{
    int c = a, d = b;
    while(a != b)
    {
        if(a < b)
            a = a+c;
        else
            b = b+d;
    }
    return a;
}
</syntaxhighlight>
'''Ans''':



'''43. What is the following function doing?'''
<syntaxhighlight lang="c">
int foo( int a, int b)
{
    int c = a-b;
    c = c&(0x80000000);
    return (!c)*a +(!!c)*b;
}
</syntaxhighlight>
'''Ans''':



'''44. What is the following function doing?'''
<syntaxhighlight lang="c">
unsigned fun(unsigned a, unsigned b)
{
    int i;
    unsigned  j = 0;
    for(i = 0; i < 32; i++)
    {
        j <<= 1;
        j += !!(a & 0x80000000);
        a <<= 1;
        if(j >=b)
        {
            j -= b;
            a++;
        }
    }
    return a;
}
</syntaxhighlight>
'''Ans''':



'''45. What is the following function doing?'''
<syntaxhighlight lang="c">
unsigned fun(unsigned int a)
{
    unsigned int i, x = 0, y = 0, z = 0;
    for(i = 0; i < 16; i++)
    {
       	y <<= 2;
       	y += !!(a & 0x80000000) << 1;
       	y += !!(a & 0x40000000);
       	a <<= 2;
       	x = x + (x&1);
       	x <<= 1;
       	z <<= 1;
       	if(x + 1 <= y)
       	{
            x++;
            z++;
	    y-=x;
        }
    }
    return z;
}
</syntaxhighlight>
'''Ans''':



	 	 	 	
'''46. Write the code to dynamically allocate a 2-D array of size m x n.'''

'''Ans''':




'''47. Declare a pointer to a function accepting an integer and returning void.'''

'''Ans''':



'''48. Write the condition so that the below code outputs <math>\unicode{x201C}</math>Hello World<math>\unicode{x201D}</math>.'''
<syntaxhighlight lang="c">
#include<stdio.h>
int main()
{
    if(<condition>)
    {
	printf("Hello ");
    }
    else
    {
	printf("World\n");
    }

    return 0;
}
</syntaxhighlight>
'''Ans''':


'''49. Write a one line code to check if a number is a power of 2.'''

'''Ans''':



'''50. Write a one line code to invert the last four bits of an integer.'''

'''Ans''':



<div class="fb-like"  data-layout="standard" data-action="like" data-show-faces="false" data-share="true" ></div>


<div class="fb-share-button"  data-layout="standard"  data-type="button_count"></div>



<disqus/>


[[Category:Algorithms & Data Structures]]
[[Category:Code]]