printf sleep \n

Question

I was trying something when I saw this strange behavior. Can someone please explain it to me.

#include<stdio.h>
int main()
{
    printf("utkarsh");
    sleep(10);
    printf("dixit");
}

The expected output is print "utkarsh" then wait for 10 seconds, print "dixit" next to it. But what I observed was that it waits for 10 seconds and the prints "utkarshdixit".

If I add a \\n at end of utkarsh, it works as expected.

printf("utkarsh\n");

Could someone help me understand why am I seeing such behavior ?

Answer 1

you're encoutering buffering.

try to do

fflush(stdout);

in front of the sleep

Answer 2

printf is buffering until you decide to write a '\\n' .

You can use : flush to force to print

Answer 3

Here, try this

#include<stdio.h>
int main()
{
    printf("utkarsh");
    fflush(stdout);
    sleep(10);
    printf("dixit");
}

There's buffering of the standard out going on. you have to explicitly flush it.

Answer 4

There is buffering in stdout stream. Hence you need to flush once before sleep.

But when you used a '\\n', the c run-time automatically flushes the stdout buffer for you. Hence you see this behaviour