getc, getwc

[アーティクル]
12/18/2017

The latest version of this topic can be found at getc, getwc.

Read a character from a stream.

Syntax

int getc(   
   FILE *stream   
);  
wint_t getwc(   
   FILE *stream   
);

Parameters

stream
Input stream.

Return Value

Returns the character read. To indicate a read error or end-of-file condition, getc returns EOF, and getwc returns WEOF. For getc, use ferror or feof to check for an error or for end of file. If stream is NULL, getc and getwc invoke the invalid parameter handler, as described in Parameter Validation. If execution is allowed to continue, these functions return EOF (or WEOF forgetwc) and set errno to EINVAL.

See _doserrno, errno, _sys_errlist, and _sys_nerr for more information on these, and other, error codes.

Remarks

Each routine reads a single character from a file at the current position and increments the associated file pointer (if defined) to point to the next character. The file is associated with stream.

These functions lock the calling thread and are therefore thread-safe. For a non-locking version, see _getc_nolock, _getwc_nolock.

Routine-specific remarks follow.

Routine	Remarks
`getc`	Same as `fgetc`, but implemented as a function and as a macro.
`getwc`	Wide-character version of `getc`. Reads a multibyte character or a wide character according to whether `stream` is opened in text mode or binary mode.

Generic-Text Routine Mappings

TCHAR.H routine	_UNICODE & _MBCS not defined	_MBCS defined	_UNICODE defined
`_gettc`	`getc`	`getc`	`getwc`

Requirements

Routine	Required header
`getc`	<stdio.h>
`getwc`	<stdio.h> or <wchar.h>

For additional compatibility information, see Compatibility in the Introduction.

Example

// crt_getc.c  
// Use getc to read a line from a file.  
  
#include <stdio.h>  
  
int main()  
{  
    char buffer[81];  
    int i, ch;  
    FILE* fp;  
  
    // Read a single line from the file "crt_getc.txt".   
  
    fopen_s(&fp, "crt_getc.txt", "r");  
    if (!fp)  
    {  
       printf("Failed to open file crt_getc.txt.\n");  
       exit(1);  
    }  
  
    for (i = 0; (i < 80) && ((ch = getc(fp)) != EOF)  
                         && (ch != '\n'); i++)  
    {  
        buffer[i] = (char) ch;  
    }  
  
    // Terminate string with a null character   
    buffer[i] = '\0';  
    printf( "Input was: %s\n", buffer);  
  
    fclose(fp);  
}

Input: crt_getc.txt

Line one.  
Line two.

Output

Input was: Line one.

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