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Top 50 C Programming MCQs

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C is a Procedural Programming Language, mostly written to code an Operating System. C is one of the most famous programming languages and is the forefather of C++, one of the most widely used programming languages today. It has many features some of which are listed below:

  • Easy to understand.
  • Efficient Memory Usage.
  • Usage of Pointers.
  • Fast.
  • Structured Programming Language.
  • Mid-Level Programming Language.
  • Portable on all machines.
  • Rich user library.

Components of a C Program:

The main components constituting a C program are listed below:

  • Header Files: A header file is a file that has an extension .h and contains C function declarations and macros, which are to be shared between several source files, hence allowing reusability and hence more efficiency in building up programming logic.
  • Main Method: The main method is a function from where the program execution starts in C.
  • Program Body: The program body is the main part of the program where all the programming logic is written. It includes all the variable declarations, the program logic(loops, conditional statements, function calls, etc), and finally the return statement terminating the program.
1. 

 What is the range of values that can be stored by int datatype in C?

2. 

What will be the output of the following code snippet?

#include <stdio.h>
int main() {
	int a = 3, b = 5;
	int t = a;
	a = b;
	b = t;
	printf("%d %d", a, b);
	return 0;
}
3. 

How is an array initialized in C language?

4. 

What is the output of the following code snippet?

#include <stdio.h>
int main() {
	int a[] = {1, 2, 3, 4};
	int sum = 0;
	for(int i = 0; i < 4; i++) {
	    sum += a[i];
	}
	printf("%d", sum);
	return 0;
}
5. 

What is the output of the following code snippet?

int main() {
	int sum = 2 + 4 / 2 + 6 * 2;
	printf("%d", sum);
	return 0;
}
6. 

How is the 3rd element in an array accessed based on pointer notation?

7. 

How are String represented in memory in C?

8. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve() {
    int a[] = {1, 2, 3, 4, 5};
    int sum = 0;
    for(int i = 0; i < 5; i++) {
        if(i % 2 == 0) {
            sum += *(a + i);
        }
        else {
            sum -= *(a + i);
        }
    }
    printf("%d", sum);
}
int main() {
	solve();
	return 0;
}
9. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve() {
    int first = 10, second = 20;
    int third = first + second;
    {
        int third = second - first;
        printf("%d ", third);
    }
    printf("%d", third);
}
int main() {
	solve();
	return 0;
}
10. 

What is the disadvantage of arrays in C?

11. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve() {
    int a = 3;
    int res = a++ + ++a + a++ + ++a;
    printf("%d", res);
}
int main() {
	solve();
	return 0;
}
12. 

What will be the value of x in the following code snippet?

#include <stdio.h>
void solve() {
    int x = printf("Hello");
    printf(" %d", x);
}
int main() {
	solve();
	return 0;
}
13. 

What does the following declaration indicate?

int x: 8;

14. 

Which of the following is the proper syntax for declaring macros in C?

15. 

Which of the following is an exit controlled loop?

16. 

What is the size of the int data type (in bytes) in C?

17. 

What will be the output of the following code snippet?

#include <stdio.h>
void swap(int *a, int *b) {
    int t = *a;
    *a = *b;
    *b = t;
}
void solve() {
    int a = 3, b = 5;
    swap(&a, &b);
    printf("%d %d", a, b);
}
int main() {
	solve();
	return 0;
}
18. 

How to declare a double-pointer in C?

19. 

If p is an integer pointer with a value 1000, then what will the value of p + 5 be?

20. 

What will be the output of the following code snippet?

#include <stdio.h>
#define VAL 3 * (2 + 6)
void solve() {
    int a = 10 + VAL;
    printf("%d", a);
}
int main() {
	solve();
	return 0;
}
21. 

Which of the following are not standard header files in C?

22. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve() {
    printf("%d %d", (023), (23));
}
int main() {
    solve();
	return 0;
}
23. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve() {
    printf("%d %d %d", (076), (28), (0x87));
}
int main() {
    solve();
	return 0;
}
24. 

What will be the result of the following code snippet?

#include <stdio.h>
void solve() {
    char ch[10] = "abcdefghij";
    int ans = 0;
    for(int i = 0; i < 10; i++) {
        ans += (ch[i] - 'a');
    }
    printf("%d", ans);
}
int main() {
    solve();
	return 0;
}
25. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve() {
    bool ok = false;
    printf(ok ? "YES" : "NO");
}
int main() {
    solve();
	return 0;
}
26. 

In which of the following languages is function overloading not possible?

27. 

Which of the following function is used to open a file in C++?

28. 

Which of the following are correct file opening modes in C?

29. 

What is the return type of the fopen() function in C?

30. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve() {
    int ch = 2;
    switch(ch) {
        case 1: printf("1 ");
        case 2: printf("2 ");
        case 3: printf("3 ");
        default: printf("None");
    }
}
int main() {
    solve();
	return 0;
}
31. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve() {
    int x = 1, y = 2;
    printf(x > y ? "Greater" : x == y ? "Equal" : "Lesser");
}
int main() {
    solve();
	return 0;
}
32. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve() {
    int n = 24;
    int l = 0, r = 100, ans = n;
    while(l <= r) {
        int mid = (l + r) / 2;
        if(mid * mid <= n) {
            ans = mid;
            l = mid + 1;
        }
        else {
            r = mid - 1;
        }
    }
    printf("%d", ans);
}
int main() {
    solve();
	return 0;
}
33. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve() {
    printf("%d ", 9 / 2);
    printf("%f", 9.0 / 2);
}
int main() {
    solve();
	return 0;
}
34. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve() {
    int x = 2;
    printf("%d", (x << 1) + (x >> 1));
}
int main() {
    solve();
	return 0;
}
35. 

What will be the output of the following code snippet?

#include <stdio.h>
#define VAL 5
int getInput() {
    return VAL;
}
void solve() {
    const int x = getInput();
    printf("%d", x);
}
int main() {
    solve();
	return 0;
}
36. 

How to find the length of an array in C?

37. 

Which of the following is not a storage class specifier in C?

38. 

What will be the output of the following code snippet?

#include <stdio.h>
void solve(int x) {
    if(x == 0) {
        printf("%d ", x);
        return;
    }
    printf("%d ", x);
    solve(x - 1);
    printf("%d ", x);
}
int main() {
    solve(3);
	return 0;
}
39. 

What will be the output of the following code snippet?

#include <stdio.h>
int search(int l, int r, int target, int a[]) {
    int mid = (l + r) / 2;
    if(a[mid] == target) {
        return mid;
    }
    else if(a[mid] < target) {
        return search(mid + 1, r, target, a);
    }
    else {
        return search(0, mid - 1, target, a);
    }
}
void solve() {
    int a[] = {1, 2, 3, 4, 5};
    printf("%d", search(0, 5, 3, a));
}
int main() {
    solve();
	return 0;
}
40. 

What will be the output of the following code snippet?

#include <stdio.h>
int get(int n) {
    if(n <= 1) {
        return n;
    }
    return get(n - 1) + get(n - 2);
}
void solve() {
    int ans = get(6);
    printf("%d", ans);
}
int main() {
    solve();
	return 0;
}
41. 

What is the output of the following code snippet?

#include <stdio.h>
#include<stdlib.h>
void set(int *to) {
    to = (int*)malloc(5 * sizeof(int));
}
void solve() {
    int *ptr;
    set(ptr);
    *ptr = 10;
    printf("%d", *ptr);
}
int main() {
    solve();
	return 0;
}
42. 

Which of the following will occur if we call the free() function on a NULL pointer?

43. 

Which of the following should be used to free memory from a pointer allocated using the “new” operator?

44. 

Which data structure is used to handle recursion in C?

45. 

What will be the output of the following code snippet?

#include <stdio.h>
#define CUBE(x) x * x * x
void solve() {
    int ans = 216 / CUBE(3);
    printf("%d", ans);
}
int main() {
    solve();
	return 0;
}
46. 

What will be the output of the following code snippet?

#include <stdio.h>
struct School {
    int age, rollNo;
};
void solve() {
    struct School sc;
    sc.age = 19;
    sc.rollNo = 82;
    printf("%d %d", sc.age, sc.rollNo);
}
int main() {
    solve();
	return 0;
}
47. 

Which of the following is not true about structs in C?

48. 

What will be the output of the following code snippet?

#include <stdio.h>
struct School {
    int age, rollNo;
};
void solve() {
    struct School sc;
    sc.age = 19;
    sc.rollNo = 82;
    printf("%d", (int)sizeof(sc));
}
int main() {
    solve();
	return 0;
}
49. 

 What will be the output of the following code snippet?

#include <stdio.h>
union School {
    int age, rollNo;
    double marks;
};
void solve() {
    union School sc;
    sc.age = 19;
    sc.rollNo = 82;
    sc.marks = 19.04;
    printf("%d", (int)sizeof(sc));
}
int main() {
    solve();
	return 0;
}
50. 

What will be the output of the following code snippet?

#include <stdio.h>
#include<string.h>
void solve() {
    char s[] = "Hello";
    printf("%s ", s);
    char t[40];
    strcpy(t, s);
    printf("%s", t);
}
int main() {
    solve();
	return 0;
}
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