How to detect php errors

Error handling is an important part when creating scripts and web applications. If your code lacks error detection coding, the program will look unprofessional and open the door to security risks.

Basic error handling: Using the die() function

The first example shows a simple script that opens a text file : (Recommended learning: PHP Video Tutorial)

<?php
$file=fopen("welcome.txt","r");
?>

If the file does not exist, you will get an error similar to this:

Warning: fopen(welcome.txt) [function.fopen]: failed to open stream: 
No such file or directory in C:\webfolder\test.php on line 2

In order to avoid users getting errors similar to the above message, we check whether the file exists before accessing it:

<?php
if(!file_exists("welcome.txt"))
 {
 die("File not found");
 }
else
 {
 $file=fopen("welcome.txt","r");
 }
?>

Now, if the file does not exist, you will get an error message like this:

File not found

Compared to the previous code, the above The code is more efficient because it uses a simple error handling mechanism that terminates the script after an error.

However, simply terminating the script is not always appropriate. Let's examine alternative PHP functions for handling errors.

Create a custom error handler

Creating a custom error handler is very simple. We simply created a dedicated function that can be called when an error occurs in PHP.

The function must be able to handle at least two parameters (error level and error message), but can accept up to five parameters (optional: file, line-number and error context):

error_function(error_level,error_message,
error_file,error_line,error_context)

Trigger Error

It is useful to trigger an error when the user inputs invalid data in the script. In PHP, this task is accomplished by trigger_error().

Error Logging

By default, PHP sends error logs to the server's error logging system or file according to the error_log configuration in php.ini. By using the error_log() function, you can send error records to a specified file or remote destination.

Emailing yourself an error message is a good way to get notified of a specified error.

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