Questions and answers on how to operate PHP files

$filename="test.dat"; //Define the operation file
$delline=3; //The number of lines to be deleted
if(!file_exsits($filename)){
die ("The specified file was not found! The operation was interrupted!");
}
$farray=file($filename);//Read file data into the array
for($tmpa=0;$Tmpaif(strcmp($Tmpa+1,$delline)==0){
//Determine the deleted row
continue;
}
//Reorganized data
$newfp.=$farray [$Tmpa]."rn";
}
$fp=@fopen($filename,"a") or die("Failed to open file $filename in writing mode");//We open the file in writing mode
@ fputs($fp,$newfp) or die("File writing failed");
@fclose($fp);
?>

The above code demonstrates deleting a line of file, but If you look carefully, it actually provides you with related reminders for other file operations~

Q: How do I keep the error from showing up when I try to open a file that doesn't exist to avoid leaking my path! ! Answer: Add the @ symbol before the method you want to open the file to block errors. @ is a special symbol provided by PHP to block error messages. Or you can add error_reporting(0); before the step to be performed (usually at the top of the page) to block the display of all error messages on the page. A not recommended method is to modify php.ini (except ISP)

Q: I am using a virtual host, how can I prevent other users from stealing my data? Answer: It is recommended that ISP modify open_basedir in php.ini to limit it. The not recommended ISP setting is to add file operations such as fopen and file to disable_function.

Q: Why can’t I delete these files when I log in via FTP to delete them after I create them with PHP? ? Answer: Mainly because the files created by PHP belong to the WEB user group, that is, the files created do not belong to your FTP user! ! ! The solution to this problem is to use chmod, unlink, etc. of the PHP program. It is recommended that users remember to chmod file permissions when using PHP to create files. The recommended value is 777

Q: How to use text files as data warehouse? Some guestbooks, forums, etc. all use this! Answer: In fact, this mainly uses file and is a typical example of data reading and segmentation combined with explode.

Q: How to change the file name? Answer: rename();

Q: How to delete files? Answer: unlink(); exec("del(rm -vf) filename"); Note: rm -vf is for use under Linux

Q: How to clear files? Answer: Use fopen(filename,"w"); or exec("echo '' > filename");

Q: How to edit file content? Answer: I remember that I once answered a question about deleting file content. In fact, editing the content only requires variable substitution on the basis of deleting the content. You can look up and change the above continue to replace the variable data. Articles you may be interested in: An example of php file operation code Small example of php file operation A nice php class for text file operations Detailed explanation of directory and file operations in php An example tutorial on php directory and file operations