Why I couldnt work with the gcc compiler without ‘\n’ in printf?

I have written a printf() statement like below:

printf("hello\n");

this works fine when built using Linux' gcc compiler. However if I write

printf("hello");

the print doesn't appear on the screen. There is some buffering mechanism it seems?

Answer :

Even if buffering isn't a problem, if you don't print the newline your shell's prompt might be clobbering the output.

you are for example using gcc in a unix shell and at the end of your program do printf("hello") it won't print a newline before your shells prompt is displayed. The prompt will be printed on that same line, sometimes overwriting the entire line depending on kind of prompt you have set up.