The rewind() function in PHP is an inbuilt function which is used to set the position of the file pointer to the beginning of the file.
Any data written to a file will always be appended if the file is opened in append (“a” or “a+”) mode regardless of the file pointer position.
The file on which the pointer has to be edited is sent as a parameter to the rewind() function and it returns True on success or False on failure.
Syntax:
rewind(file)
Parameters Used:
The rewind() function in PHP accepts one parameter.
- file : It is a mandatory parameter which specifies the file to be edited.
Return Value:
It returns True on success or False on failure.
Errors And Exception:
- The rewind() function generates an E_WARNING level error on failure.
- The stream must be “seekable” for using the rewind() function.
- If the file is opened in append mode, the data written will be appended regardless of the position of the pointer.
Examples:
Input: $myfile = fopen("gfg.txt", "r"); fseek($myfile, "10"); rewind($myfile); fclose($file); Output: 1 Input : $myfile = fopen("gfg.txt", "r+"); fwrite($myfile, 'geeksforgeeks'); rewind($myfile); fwrite($myfile, 'portal'); rewind($myfile); echo fread($myfile, filesize("gfg.txt")); fclose($myfile); Output : portalforgeeks Here all characters of the file as it is after rewind "portal"
Below are the programs to illustrate the rewind() function.
Program 1
<?php $myfile = fopen ( "gfg.txt" , "r" );
// Changing the position of the file pointer fseek ( $myfile , "10" );
// Setting the file pointer to 0th // position using rewind() function rewind ( $myfile );
// closing the file fclose( $file );
?> |
Output:
1
Program 2
<?php $myfile = fopen ( "gfg.txt" , "r+" );
// writing to file fwrite( $myfile , 'geeksforgeeks a computer science portal' );
// Setting the file pointer to 0th // position using rewind() function rewind ( $myfile );
// writing to file on 0th position fwrite( $myfile , 'geeksportal' );
rewind ( $myfile );
// displaying the contents of the file echo fread ( $myfile , filesize ( "gfg.txt" ));
fclose( $myfile );
?> |
Output:
geeksportalks a computer science portal
Reference:
http://php.net/manual/en/function.rewind.php