sleep() in infinite while loop not printing value if not ended with \n

Question

This code work's fine :

int main()
{
while(1){

printf("hi\n");
sleep(1);
}

return 0;
}

Output: hi hi hi ...

but when we remove '\n' it will print nothing?

int main()
{
while(1){

printf("hi");
sleep(1);
}

return 0;
}

Output: NO OUTPUT

Plz anyone give explaination of this behaviour :)

Check this: http://stackoverflow.com/questions/1716296/why-does-printf-not-flush-after-the-call-unless-a-newline-is-in-the-format-strin — babon, Jul 18 '16 at 06:56

score 1 · Accepted Answer · answered Jul 18 '16 at 06:55

1

stdout if buffered by default, so to flush it you should out \n or fill that internal buffer completely. If such behavior is undesired - you can flush it manually with fflush(stdout) or turn off buffering with setbuffer(stdout, NULL, 0).

answered Jul 18 '16 at 06:55

Sergio

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score 0 · Answer 2 · answered Jul 18 '16 at 06:56

The reason you're not seeing anything printed is because the output is buffered.

The reason you see prints when you suffix \n is that on some systems, a newline causes the buffer to flush. You can flush stdout manually like so:

int main()
{
    while(1)
    {
        printf("hi");
        fflush(stdout);
        sleep(1);
    }
return 0;
}

sleep() in infinite while loop not printing value if not ended with \n

2 Answers2