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I want to turn off the buffering for the stdout for getting the exact result for the following code
while(1) { printf("."); sleep(1); } The code printf bunch of '.' only when buffer gets filled.
927
In C, file output is block buffered. Output to stdout is line buffered. The stderr device is unbuffered.
By default writes to stdout pass through a 4096 byte buffer, unless stdout happens to be a terminal/tty in which case it is line buffered. Hence the inconsistency between the immediate output when your program is writing to the terminal and the delayed output when it is writing to a pipe or file.
setbuf() — Control Buffering The stream pointer must refer to an open file before any I/O or repositioning has been done. If the buffer argument is NULL, the stream is unbuffered. If not, the buffer must point to a character array of length BUFSIZ, which is the buffer size that is defined in the <stdio.
Default Buffering modes:stdout is buffered (line buffered if connected to a terminal) stderr is unbuffered.
You can use the setvbuf function:
setvbuf(stdout, NULL, _IONBF, 0); The link above has been broken. Here're another links to the function.
POSIX
C/C++
75
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