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, 'neveropen');
rewind($myfile);
fwrite($myfile, 'portal');
rewind($myfile);
echo fread($myfile, filesize("gfg.txt"));
fclose($myfile);
Output : portalforneveropen
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, 'neveropen a computer science portal'); // Setting the file pointer to 0th // position using rewind() function rewind($myfile); // writing to file on 0th position fwrite($myfile, 'neveropenportal'); rewind($myfile); // displaying the contents of the file echo fread($myfile, filesize("gfg.txt")); fclose($myfile); ?> |
Output:
neveropenportalks a computer science portal
Reference:
http://php.net/manual/en/function.rewind.php
