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ff_ftell()

[FreeRTOS+FAT Standard API Reference]

ff_stdio.h
long ff_ftell( FF_FILE *pxStream );
		

Returns the current read/write position of an open file in the embedded FAT file system. The position is returned as the number of bytes from the start of the file.

Parameters:

pxStream   The file being queried. The file must have first been opened using a call to ff_fopen().
Returns:

If pxStream is not NULL then the file’s current read/write position is returned. The returned value is the number of bytes the file’s read/write position is from the start of the file.

If pxStream is NULL then -1 is returned.

Example usage:


void vSampleFunction( char *pcFileName, char *pcBuffer )
{
FF_FILE *pxFile;
long lPosition;

/* Open the file specified by the pcFileName parameter. */
pxFile = ff_fopen( pcFileName, “r” );

/* Expect the file position to be 0. */
lPosition = ff_ftell( pxFile );
configASSERT( lPosition == 0 );

/* Read one byte. */
ff_fread( pcBuffer, 1, 1, pxFile );

/* Expect the file position to be 1. */
lPosition = ff_ftell( pxFile );
configASSERT( lPosition == 1 );

/* Read another byte. */
ff_fread( pcBuffer, 1, 1, pxFile );

/* Expect the file position to be 2. */
lPosition = ff_ftell( pxFile );
configASSERT( lPosition == 2 );

/* Close the file again. */
ff_fclose( pxFile );
}

Example use of the ff_ftell() API function


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