_fgetc_nolock, _fgetwc_nolock

Article
06/05/2017

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The latest version of this topic can be found at _fgetc_nolock, _fgetwc_nolock.

Reads a character from a stream without locking the thread.

Syntax

int _fgetc_nolock(   
   FILE *stream   
);  
wint_t _fgetwc_nolock(   
   FILE *stream   
);

Parameters

stream
Pointer to the FILE structure.

Return Value

Seefgetc, fgetwc.

Remarks

_fgetc_nolock and _fgetwc_nolock are identical to fgetc and fgetwc, respectively, except that they are not protected from interference by other threads. They might be faster because they do not incur the overhead of locking out other threads. Use these functions only in thread-safe contexts such as single-threaded applications or where the calling scope already handles thread isolation.

Generic-Text Routine Mappings

Tchar.h routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
`_fgettc_nolock`	`_fgetc_nolock`	`_fgetc_nolock`	`_fgetwc_nolock`

Requirements

Function	Required header
`_fgetc_nolock`	<stdio.h>
`_fgetwc_nolock`	<stdio.h> or <wchar.h>

For more compatibility information, see Compatibility in the Introduction.

Example

// crt_fgetc_nolock.c  
// This program uses getc to read the first  
// 80 input characters (or until the end of input)  
// and place them into a string named buffer.  
  
#include <stdio.h>  
#include <stdlib.h>  
  
int main( void )  
{  
   FILE *stream;  
   char buffer[81];  
   int  i, ch;  
  
   // Open file to read line from:   
   if( fopen_s( &stream, "crt_fgetc_nolock.txt", "r" ) != 0 )  
      exit( 0 );  
  
   // Read in first 80 characters and place them in "buffer":  
   ch = fgetc( stream );  
   for( i=0; (i < 80 ) && ( feof( stream ) == 0 ); i++ )  
   {  
      buffer[i] = (char)ch;  
      ch = _fgetc_nolock( stream );  
   }  
  
   // Add null to end string   
   buffer[i] = '\0';  
   printf( "%s\n", buffer );  
   fclose( stream );  
}

Input: crt_fgetc_nolock.txt

Line one.  
Line two.

Output

Line one.  
Line two.

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