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Name

getc, getc_unlocked, getchar, getchar_unlocked, fgetc, getw - get character or word from a stream

Synopsis

#include <stdio.h>

int getc(FILE *stream);

int getc_unlocked(FILE *stream);

int getchar(void);

int getchar_unlocked(void);

int fgetc(FILE *stream);

int getw(FILE *stream);

MT-Level

See the NOTES section of this page.

Description

getc() returns the next character (that is, byte) from the named input stream (see intro(3) ) as an unsigned char converted to an int. It also moves the file pointer, if defined, ahead one character in stream. getchar() is defined as getc(stdin). getc() and getchar() are macros.

getc_unlocked() and getchar_unlocked() are respectively variants of getc() and getchar() that do not lock the stream. It is the caller’s responsibility to acquire the stream lock before calling these functions and releasing the lock afterwards; see flockfile(3S) and stdio(3S) .

fgetc() behaves like getc(), but is a function rather than a macro. fgetc() runs more slowly than getc() , but it takes less space per invocation and its name can be passed as an argument to a function.

getw() returns the next word (that is, integer) from the named input stream. getw() increments the associated file pointer, if defined, to point to the next word. The size of a word is the size of an integer and varies from machine to machine. getw() assumes no special alignment in the file.

Return Values

These functions return the constant EOF at end-of-file or upon an error and set the EOF or error indicator of stream, respectively. Because EOF is a valid integer, ferror() should be used to detect getw() errors.

See Also

intro(3) , fclose(3S) , ferror(3S) , flockfile(3S) , fopen(3S) , fread(3S) , gets(3S) , putc(3S) , scanf(3S) , stdio(3S) , ungetc(3S)

Notes

If the integer value returned by getc(), getchar(), or fgetc() is stored into a character variable and then compared against the integer constant EOF , the comparison may never succeed, because sign-extension of a character on widening to integer is implementation dependent.

The macro version of getc() evaluates a stream argument more than once and may treat side effects incorrectly. In particular, getc(*f++) does not work sensibly. Use fgetc() instead.

Because of possible differences in word length and byte ordering, files written using putw() are implementation dependent, and may not be read using getw() on a different processor.

Functions exist for all the above-defined macros. To get the function form, the macro name must be undefined (for example, #undef getc).

fgetc(), getc(), getchar(), getw(), and ungetc() are MT-Safe in multi-thread applications. getc_unlocked() and getchar_unlocked() are unsafe in multi-thread applications.

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