4.48 putchar_unlocked—non-thread-safe version of putchar (macro)

Synopsis

     #include <stdio.h>
     int putchar_unlocked(int ch);
     

Description
putchar_unlocked is a non-thread-safe version of putchar declared in stdio.h. putchar_unlocked may only safely be used within a scope protected by flockfile() (or ftrylockfile()) and funlockfile(). These functions may safely be used in a multi-threaded program if and only if they are called while the invoking thread owns the ( FILE *) object, as is the case after a successful call to the flockfile() or ftrylockfile() functions. If threads are disabled, then putchar_unlocked is equivalent to putchar.

Supporting OS subroutines required: close, fstat, isatty, lseek, read, sbrk, write.