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cansi-c

Code before while(1) does not run

I have code like this below:

#include <stdio.h>

int main(int argc, char *argv[]) {
    printf("hello");

    while(1){
        // whatever here
    }
}

and the question is: why the first instruction is skipped? It runs only the loop, hello is never printed. I compiled it with gcc and g++ with the same result.

Solution

  • Your assumption is wrong, your code does run, only stdout is not flushed, but buffered.

    Use fflush(stdout) after printf("hello"), this forces stdout to be printed.

    And, as @Bathsheba pointed out, also a newline character ("\n") within the printf forces it to flush, which is explained in this SO question.