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Inside this article we will see the concept i.e Types of Programming Errors of PHP. Article contains the classified information i.e What are the types of errors in PHP?

A programming error in PHP refers to a mistake or fault in the code that causes the program to malfunction or produce incorrect results. These errors can occur due to a variety of factors, such as incorrect syntax or logical issues, and can be classified into different types, including syntax errors, logical errors, and runtime errors.

Parse Error
Fatal Error
Warning Error
Notice Error

Let’s get started.

What are Programming Errors of PHP?

A program error, also known as a programming error, is a fault or mistake in the code that can cause the program to malfunction or produce incorrect results.

Program errors can be caused by several factors and can take various forms, such as syntax errors and logic errors. Syntax errors occur when the code violates the syntax rules of the programming language, whereas logic errors occur when there is an issue in the program’s algorithm or logic.

In PHP, there are various types of errors, but the main ones can be classified into four categories.

1. Parse Error or Syntax Error of PHP

In PHP, a parse error or syntax error occurs when the PHP parser encounters an error while trying to parse or interpret the PHP code. This can happen when the code is not properly written according to the syntax rules of the PHP language.

When a parse error occurs, the PHP interpreter will stop executing the code and display an error message that indicates the location of the error in the code. This error message can be useful for identifying and correcting the problem in the code.

Here’s an example of a parse error:

<?php
echo "Hello World!'
?>

This will print this Output:

PHP Parse error: syntax error, unexpected end of file, expecting variable (T_VARIABLE) or ${ (T_DOLLAR_OPEN_CURLY_BRACES) or {$ (T_CURLY_OPEN) in /home/OZbiOr/prog.php on line 5

In this example, the closing quote is missing in the string “Hello World!“. This will cause a parse error because the PHP parser is unable to parse the code due to the missing quote. The error message will indicate the line number where the error occurred and provide a description of the error.

It’s important to note that even a small mistake in the code, such as a missing semicolon or a misplaced bracket, can cause a parse error. It’s important to carefully review and test your code to ensure that it is free of syntax errors before deploying it to a production environment.

2. Fatal Error of PHP

In PHP, a fatal error is an error that occurs when the PHP parser or engine is unable to continue the execution of a script due to a severe error. Fatal errors usually occur during the script’s execution and can result in the termination of the script’s execution.

<?php

function add($x, $y)
{
	$sum = $x + $y;
	echo "sum = " . $sum;
}
$x = 0;
$y = 20;
add($x, $y);

diff($x, $y);
?>

This will print this Output:

PHP Fatal error:  Uncaught Error: 
Call to undefined function diff() 
in /home/prog.php:12

Stack trace:
#0 {main}
  thrown in /home/prog.php on line 12

Some common causes of fatal errors in PHP include the following:

Syntax errors: These are common errors that occur when the PHP parser cannot understand the code due to incorrect syntax.
Memory exhaustion: When a PHP script runs out of memory, a fatal error occurs, as the script cannot continue to execute without more memory.
Maximum execution time exceeded: If a script takes too long to execute, a fatal error can occur, as the maximum execution time has been exceeded.
Undefined functions or variables: When a PHP script tries to call a function or use a variable that has not been defined, a fatal error can occur.

When a fatal error occurs in PHP, the script is terminated immediately, and an error message is displayed. The error message usually contains information about the error’s cause and location in the code, making it easier for developers to identify and fix the problem.

3. Warning Error of PHP

In PHP, warning errors are errors that do not prevent a script from executing but may indicate a problem or potential issue that needs to be addressed.

Warning errors are less severe than fatal errors, and they usually occur when a script tries to do something that is not recommended or best practice.

A Basic Example

<?php

$x = "Hello Online Web Tutor";

include ("file.php");

echo $x . "Computer science chapters";

?>

This will print this Output:

PHP Warning:  include(gfg.php): failed to 
open stream: No such file or directory in 
/home/prog.php on line 5
PHP Warning:  include(): Failed opening 'file.php'
 for inclusion (include_path='.:/usr/share/php') in 
/home/prog.php on line 5

Some examples of warning errors in PHP include:

Use of undefined variables: This warning occurs when a script tries to use a variable that has not been defined.

<?php
// This script will produce a warning because $var is not defined
echo $var;
?>

Use of deprecated functions: This warning occurs when a script uses a function that has been deprecated and is no longer recommended for use.

<?php
// This script will produce a warning because the ereg() function is deprecated
if (ereg('pattern', $string)) {
  // do something
}
?>

Incorrect function parameters: This warning occurs when a function is called with incorrect or invalid parameters.

<?php
// This script will produce a warning because the substr() function is called with invalid parameters
$string = 'Hello World';
echo substr($string, 0, -10);
?>

When a warning error occurs in PHP, the script continues to execute, but a warning message is displayed. This message contains information about the warning and its location in the code, making it easier for developers to identify and fix the issue.

It’s important to pay attention to warning errors in PHP, as they can indicate potential problems that may lead to more severe errors in the future.

4. Notice Error of PHP

In PHP, notice errors are relatively less severe than warnings and do not prevent a script from executing. Notice errors indicate non-critical issues in the code that may require attention or correction.

A Basic Example:

<?php

$x = "Hello Online Web Tutor";

echo $x;

echo $message;
?>

This will print this Output:

Error:

PHP Notice:  Undefined variable: message in 
/home/prog.php on line 5

Output:

Hello Online Web Tutor

Some examples of notice errors in PHP include:

Undefined array indexes: This notice occurs when a script tries to access an array index that does not exist.

<?php
// This script will produce a notice because the index "b" does not exist in the $array array
$array = array('a' => 1, 'c' => 3);
echo $array['b'];
?>

Using a variable that is not initialized: This notice occurs when a script tries to use a variable that has not been initialized.

<?php
// This script will produce a notice because the $var variable is not initialized
echo $var;
?>

Incorrect property access: This notice occurs when a script tries to access a property that does not exist.

<?php
// This script will produce a notice because the $object object does not have a "property" property
$object = new stdClass;
echo $object->property;
?>

Notice errors in PHP are informational in nature and do not necessarily require immediate attention.

However, it’s important to fix these issues to ensure that the code is clean and efficient. Notice errors may also be indicative of potential problems that could cause more severe errors in the future.

We hope this article helped you to learn Types of Programming Errors of PHP in a very detailed way.

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