Consider the following C program: #include <stdio.h> int r(){ static int…

2019

Consider the following C program:

#include <stdio.h>
int r(){
    static int num=7;
    return num--;
}

int main(){
    for (r();r();r())
         printf(“%d”,r());
    return 0;
}

Which one of the following values will be displayed on execution of the programs?

Answer: B. 52 — Key idea: the function returns the current value of a static variable and then decrements it (post-decrement). Each call updates the same static variable…

  1. A.

    41

  2. B.

    52

  3. C.

    63

  4. D.

    630

Attempted by 223 students.

Show answer & explanation

Correct answer: B

Key idea: the function returns the current value of a static variable and then decrements it (post-decrement). Each call updates the same static variable sequentially.

  • Initial static num = 7.

  • Initialization call r() returns 7, then num becomes 6.

  • Condition call r() returns 6 (nonzero), then num becomes 5 — loop enters.

  • printf's call r() returns 5 (printed first digit), then num becomes 4.

  • Increment call r() returns 4, then num becomes 3.

  • Next condition call r() returns 3 (nonzero), then num becomes 2 — second iteration begins.

  • printf's call r() returns 2 (printed second digit), then num becomes 1.

  • Increment call r() returns 1, then num becomes 0.

  • Next condition call r() returns 0 (loop stops), then num becomes -1.

Result: the program prints 52.

Common pitfall: confusing pre-decrement with post-decrement or misordering the sequence of function calls in the for loop. Trace each call in order to avoid mistakes.

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