Why does a call to printf need to be terminated by a newline ?

[Perto56]

Works:

  printf("hello world\n");

Does not work:

  printf("goodbye world !");

I have tried to find the answer in gcc´without success.

[Uwe Bonnes · Accepted solution]

That is a standard properity of stdout, it is buffered. Use stderr and output is immediate.Or fflush stdout.

[KnarfB]

It doesn't need to. But, by default printf is line buffered. This allows more efficient output if you override _write (instead of __io_putchar). It is also for historical reasons/compatability.

If you want to turn it off:

setvbuf(stdout, NULL, _IONBF, 0);

hth

KnarfB

[Perto56]

Thanks alot.