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### 4.47 `putchar`—write a character (macro)

Synopsis

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

    int _putchar_r(struct _reent *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`.