fopen

1 Description
2 Syntax
3 Parameters
4 Return
5 Examples
6 Remark
7 See Also
8 header to Include
9 Reference

Description

Opens the file specified by filename.

Syntax

FILE * fopen( const char * filename, const char * mode )

Parameters

filename: Filename
mode: Type of access permitted

Return

returns a pointer to the open file. A null pointer value indicates an error.

Examples

EX1

//This following example open files named "data.txt", and "data2.txt". It uses fclose to close "data.txt" and "data2.txt"

void test_fopen()
{
        FILE *stream, *stream2;
        
        // Open for read (will fail if file "data" does not exist)
        stream  = fopen( "c:\\data.txt", "r" );
        if( stream == NULL )
          printf( "The file 'data' was not opened\n" );
        else
          printf( "The file 'data' was opened\n" );
        
        // Open for write 
        stream2 = fopen( "c:\\data2.txt", "w+" );
        if( stream2 == NULL )
          printf( "The file 'data2' was not opened\n" );
        else
          printf( "The file 'data2' was opened\n" );
        
        // Close stream 
        if ( stream != NULL )
        {
          if( fclose( stream ) )
              printf( "The file 'data' was not closed\n" );
          else
              printf( "The file 'data' was closed\n" );
        }
        // Close stream2 
        if ( stream2 != NULL )
        {
          if( fclose( stream2 ) )
              printf( "The file 'data2' was not closed\n" );
          else
              printf( "The file 'data2' was closed\n" );
        }
}

Remark

This function opens the file specified by filename.

The character string mode specifies the type of access requested for the file, as follows:

"r" :Opens for reading. If the file does not exist or cannot be found, the fopen call fails.

"w" :Opens an empty file for writing. If the given file exists, its contents are destroyed.

"a" :Opens for writing at the end of the file (appending) without removing the EOF marker before writing new data to the file; creates the file first if it doesn?t exist.

"r+":Opens for both reading and writing. (The file must exist.)

"w+":Opens an empty file for both reading and writing. If the given file exists, its contents are destroyed.

"a+":Opens for reading and appending; the appending operation includes the removal of the EOF marker before new data is written to the file and the EOF marker is restored after writing is complete; creates the file first if it doesn?t exist.

If the filename doesn't contain file path, default of current path is %SYSTEM%\OriginC\OriginLab .