Why does printf() not print anything before sleep()?

Question

I\'m just learning C with Kernighan and Ritchie\'s book; I\'m in the basics of the fourth chapter (functions stuff). The other day I became curious about the sleep()

Answer 1

Buffering means that all the output is stored in a place (called buffer) and is output after a certain amount of data is present in it. This is done for efficiency reasons.

Some (most?) implementations clear the buffer after a newline when writing to the console, so you can also try

printf(" I like cows.\n");

instead of the call to fflush()