Output

For efficiency, writing to files under Unix is usually buffered, so printf(....) might not immediately produce bytes at stdout. Should your program crash soon after a printf() command you might never see the output. If you want to force synchronous output you can

• Use stderr (which is usually unbuffered) instead of stdout.
• Use fflush(stdout) to flush out the standard output buffer.
• Use setbuf(stdout,NULL) to stop standard output being buffered.