The ftruncate() function in PHP is an inbuilt function which is used to truncate(shorten) an open file to the specified length. The file and the new size of the file are sent as parameters to the ftruncate() function and it returns True on success and False on Failure. If size specified in the parameter is larger than the file then the file is extended with null bytes and if size specified is smaller than the file then the file is truncated to that size.
Syntax :
ftruncate(file, size)
Parameters: The ftruncate() function in PHP accepts two parameters.
- file: It is a mandatory parameter which specifies the file.
- size : It is a mandatory parameter which specifies the new size of the file.
Return Value: It returns True on success and False on Failure.
Exceptions:
- rewind() function must be used after ftruncate() function to replace file content.
- The file pointer is not changed by the ftruncate() function.
- If size specified in the parameter is larger than the file then the file is extended with null bytes and if size specified is smaller than the file then the file is truncated to that size
Below programs illustrate the ftruncate() function:
Program 1:
<?php // checking filesize before truncating echo filesize("gfg.txt"); // Opening the file $myfile = fopen("gfg.txt", "a+"); // truncating the file ftruncate($myfile, 10); // closing the file fclose($file); // Clearing cache and checking filesize again clearstatcache(); echo filesize("gfg.txt"); // closing the file fclose($myfile); ?> |
Output:
500 10
Program 2:
<?php $myfile = 'gfg.txt'; // opening file in read mode $myhandle = fopen($myfile, 'r+'); // truncating the file ftruncate($myhandle, rand(1, filesize($myfile))); // using reiwnd() to replace file content rewind($myhandle); echo fread($myhandle, filesize($myfile)); // closing the file fclose($handle); ?> |
Output:
10
Reference : http://php.net/manual/en/function.ftruncate.php
