Question 2
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The program below has a bug. Which statement correctly describes it?
#include <stdio.h>
int main(void) {
int bit = 31;
int mask = 1 << bit;
printf("%d\n", mask != 0);
return 0;
}- A bit must be unsigned
- B 1 is a signed int, and 1 << 31 does not fit in a 32-bit int – undefined behaviour; write 1u << 31 Correct
- C mask != 0 is always false
- D There is no bug
Correct Answer: Option B
The literal 1 is an int. Shifting it into the sign bit produces a value that int cannot represent, which is undefined. 1u << 31 is a well-defined unsigned 0x80000000.
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