Understand php error types and resolve them

PHP is a very popular server-side scripting language used for developing dynamic Internet applications. In PHP, errors are divided into three main categories: fatal errors, warnings, and hints. It is very important for PHP developers to understand all error types and how to handle them.

1. Fatal Error

Fatal error is one of the most serious types of PHP errors. When a fatal error occurs during PHP script execution, the code will stop executing and return a fatal Wrong message. Not handling this error will cause the script to crash completely. Here are several common fatal errors:

a. Fatal error: Call to undefined function

This fatal error means that PHP cannot find the function you are trying to call. Check that the function name and spelling are correct in your code, and make sure you have included the file where the function is located correctly.

b. Fatal error: Maximum execution time exceeded

This error indicates that the execution time of the script exceeds the maximum allowed time. Find lines of code that cause script execution to time out and try to optimize the code to reduce execution time.

c. Fatal error: Allowed memory size exhausted

This error indicates that the amount of memory used when PHP is executed exceeds the maximum amount of memory allowed in the PHP configuration file. This problem can be solved by increasing PHP's memory limit.

2. Warning

A warning is a common type of error in PHP. It means there is a problem with your code, but the code can still be executed. Although warnings won't necessarily cause your code to crash, unhandled warnings can introduce potential problems into your code. Here are a few common warnings:

a. Warning: include_once(): Failed opening 'file.php'

This warning means that you tried to include a file in your code, but the The file cannot be found or opened. Please check that the file location and path are correct, and make sure the file name is spelled correctly.

b. Warning: mysqli_query(): Couldn't fetch mysqli

This warning means that your code tried to connect to a MySQL database, but the connection failed. Check whether the database address, username and password are correct.

c. Warning: Invalid argument supplied for foreach()

This warning means that you are trying to use foreach to iterate over a non-array variable. Make sure your variable is indeed an array.

3. Tip

Tip is the least serious type of error in PHP. It means that there are some problems with your code, but these problems will not cause the code to be fatal. Error or warning. Here are a few common tips:

a. Notice: Undefined variable

This tip means that you are trying to use an undefined variable. Make sure you define and initialize a variable before you can use it in your code.

b. Notice: Trying to get property of non-object

This prompt means that you are trying to access the properties of a non-object variable. Make sure the variable is an object before you can access its properties.

c. Deprecated: mysql_connect()

This prompt means that you are using a function that is not supported by PHP 5.5. Please upgrade to the latest version of PHP and use MySQLi or PDO MySQL.

Properly handling PHP errors can help you better optimize, debug, and maintain your PHP applications. Learning how to avoid these mistakes and how to deal with them correctly will be an important step in becoming a good PHP developer.

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