Programming and Data Structures · Programming in C
Official IIT answer key · IIT Guwahati · Audited Aug 2026
GATE CSE 2018 Q21 · NAT · 1 mark
#include <stdio.h>
int counter = 0;
int calc (int a, int b) {
int c;
counter++;
if (b==3) return (a*a*a);
else {
c = calc(a, b/3);
return (c*c*c);
}
}
int main () {
calc(4, 81);
printf ("%d", counter);
}
The output of this program is ________.Key concept
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Topic notes
In GATE CS, Programming in C is tested extensively through rigorous code tracing, pointer mechanics, and fundamental semantics rather than high-level syntax trivia. Questions emphasize pointer arithmetic and multidimensional array decay, storage classes (especially static local variables), evaluation order, side effects of increment/decrement operators, parameter passing mechanisms (pass-by-value vs pass-by-reference), and recursive program state tracking. The topic features a nearly balanced split between NAT and MCQ items across 1-mark and 2-mark categories, demanding precise, bug-free execution traces without a compiler.
Full Programming in C guide →Consider the following C program: #include int counter = 0; int calc (int a, int b) int c; counter++; if (b==3) return (a*a*a); else c = calc(a, b/3); return (c*c*c); int main () calc(4, 81); printf ("%d", counter); The output of this program is …
Topic-wise GATE CS PYQs with verified steps
Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.