Programming and Data Structures · Recursion
Official IIT answer key · IISc Bangalore · Audited Aug 2026
GATE CSE 2024 Set 1 Q19 · MCQ · 1 mark
#include <stdio.h>
void fX();
int main(){
fX();
return 0;
}
void fX(){
char a;
if((a=getchar()) != '
')
fX();
if(a != '
')
putchar(a);
}
Assume that the input to the program from the command line is 1234 followed by a newline character. Which one of the following statements is CORRECT?Key concept
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Topic notes
GATE tests Recursion primarily through direct execution tracing of recursive C code snippets, stack-unwinding behavior (pre-order vs. post-order execution), and termination/infinite recursion analysis. Questions frequently incorporate static variables, pointer/reference aliasing, mutual recursion, and tree/array traversals to test whether candidates can systematically maintain call frames. In recent years, the focus has expanded from standard tracing to higher-order mathematical characterizations (e.g., finding the smallest input or maximum output value of composed recurrences).
Full Recursion guide →Consider the following C program: #include void fX(); int main() fX(); return 0; void fX() char a; if((a=getchar()) != ' ') fX(); if(a != ' ') putchar(a); Assume that the input to the program from the command line is 1234 followed by a newline character. Which one of the following statements is CORRECT?
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Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.