putchar---write a character (macro)#include <stdio.h> int putchar(int ch); int _putchar_r(void *reent, int ch);Description
putchar is a macro, defined in stdio.h. putchar
writes its argument to the standard output stream,
after converting it from an int to an unsigned char.
The alternate function _putchar_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
If successful, putchar returns its argument ch. If an error
intervenes, the result is EOF. You can use `ferror(stdin)' to
query for errors.
Portability
ANSI C requires putchar; it suggests, but does not require, that
putchar be implemented as a macro.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.