GATE 2026 CS (CS2) – Question 60

Programming and Data Structures · Programming in C · 2 marks · Numerical answer

Consider the following ANSI C program.

#include <stdio.h>
int main(){
    int *ptr, a, b, c;
    a = 5; b = 11; c = 20;
    ptr = &a; *ptr = c; ptr = &c;
    a = *(&b); c = *ptr - a;
    printf("%d", c);
    return 0;
}

The output of this program is __________. (answer in integer)

Note: Assume that the program compiles and runs successfully.

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Show answer and explanation

Correct answer: 9

Explanation

Initially $a=5$, $b=11$, and $c=20$. The statement `ptr=&a; *ptr=c;` stores 20 into $a$, so now $a=20$. Then `ptr=&c;` makes `ptr` point to $c$. Next, `a=*(&b);` assigns the value of $b$ to $a$, so $a=11$. Finally, `c=*ptr-a` means $c=c-a=20-11=9$. Therefore, the program prints 9.