In C, consider missing arguments to printf: what will actually be printed (conceptually) by this code using bit shifts? #include<stdio.h> int main() { printf("%d >> %d %d >> %d ", 4 >> 1, 8 >> 1); return 0; } Note: The format string has four %d placeholders but only two arguments.

Difficulty: Medium

Correct Answer: 2 >> 4 Garbage value >> Garbage value

Explanation:


Introduction / Context:
This question assesses understanding of printf formatting and undefined behavior when the number of conversion specifiers does not match the number of provided arguments. It also includes simple right-shift operations 4 >> 1 and 8 >> 1.



Given Data / Assumptions:

  • Two arguments are supplied for four %d placeholders.
  • 4 >> 1 equals 2; 8 >> 1 equals 4 for typical two’s complement integers.
  • Accessing additional %d values with no corresponding arguments yields undefined behavior.


Concept / Approach:
printf reads arguments from the stack/variadic argument list according to the format string. Missing arguments mean printf will fetch whatever bits happen to be present, leading to unpredictable “garbage” values for the third and fourth %d.



Step-by-Step Solution:
First %d prints 4 >> 1 = 2.Literal text " >> " appears.Second %d prints 8 >> 1 = 4.Remaining two %d consume unspecified memory → unpredictable integers.



Verification / Alternative check:
If the call were corrected to printf("%d >> %d %d >> %d\n", 4 >> 1, 1, 8 >> 1, 1), the output would be 2 >> 1 4 >> 1. As written, results beyond the first two are undefined.



Why Other Options Are Wrong:
Literal or fully defined outputs ignore the argument mismatch.“2 4” omits the format text and still ignores missing arguments.



Common Pitfalls:
Assuming printf quietly fills zeros; forgetting that varargs require a one-to-one match with conversion specifiers.



Final Answer:
2 >> 4 Garbage value >> Garbage value

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