GATE CS 2024 Set 2 — Question 36

MCQ+2 / -0.67MediumPointers & Pointer ArithmeticC ProgrammingProgramming & Data StructuresArrays & Strings in C

Programming & Data Structures → C Programming → Arrays & Strings in C

Last updated 20 August 2026

Question

What is the output of the following C program?

#include 
int main() {
 double a[2]={20.0, 25.0}, *p, *q;
 p = a;
 q = p + 1;
 printf("%d,%d", (int)(q - p), (int)(*q - *p));
 return 0;}

4,8

1,5

8,5

1,8

Correct answer

(B) 1,5

Solution

1.Pointer Arithmetic: The array a is initialized with two double values: a[0] = 20.0 and a[1] = 25.0. The pointer p is assigned the base address of the array (p = a), so it points to a[0]. The pointer q is assigned p + 1, so it points to the next element, a[1].

2.Pointer Subtraction: In C, when you subtract two pointers of the same type (q - p), the result is the number of elements of that type between the two addresses. Since q points to the element immediately following p, q - p is

1

. Casting this to (int) gives

1

3.Value Subtraction: *q dereferences to the value

25.0

, and *p dereferences to

20.0

. The expression *q - *p calculates the difference between these values:

25.0 - 20.0 = 5.0

. Casting this result to (int) gives

5

4.Final Output: The printf function uses the format string "%d,%d", resulting in the output 1,5.

GATE CS 2024 Set 2 — Question 36

Question

Correct answer

Solution

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