A Crash Course of Changes to Exception Handling in PHP 7

Major improvements in PHP 7 exception handling

PHP 7 has made significant improvements to exception handling, introducing the Throwable interface and Error class, which significantly enhances error handling capabilities. The Throwable interface is the base interface of the Exception and Error classes, allowing developers to catch all throwable errors, whether exceptions or errors. The Error class handles various internal PHP errors, including fatal and type errors, and is broken down into four subclasses: ArithmeticError, TypeError, ParseError, AssertionError, and

.

Throwable Interface

The ThrowableException interface is the parent interface of the Error and

classes, allowing you to catch any throwable errors, regardless of whether it is an exception or an error. For example:

<?php try {
    throw new Exception("这是一个异常");
} catch (Throwable $e) {
    echo $e->getMessage();
}

ParseErroror new

:

<?php try {
    $result = eval("2*'7'");
} catch (Throwable $e) {
    echo $e->getMessage();
}

ParseErrorExecute this code to get a eval() because the semicolon is missing in

.

ThrowableCustom classes cannot be implemented directly Throwable, but must extend the Exception class that implements the

interface.

Error Category

Error

Class handles PHP internal errors (fatal error or type error). It has four subclasses:

1. ArithmeticError
: Arithmetic error, such as dividing by zero.
2. TypeError
: Type error, such as assigning the value of the wrong type to a variable.
3. ParseError
: parsing error, such as syntax error.
4. AssertionErrorassert(): Assertion error, thrown when the condition in the
function is false.

ErrorBefore upgrading to PHP 7, if a custom

class is defined, its name must be changed, otherwise a fatal error will occur.

ArithmeticError

intdiv()This error occurs when performing mathematical operations. For example, use

:

<?php try {
    var_dump(intdiv(PHP_INT_MIN, -1));
} catch (ArithmeticError $e) {
    echo $e->getMessage();
}

will get the "Division of PHP_INT_MIN by -1DivisionByZeroError" error. ArithmeticError is a subclass of

and is thrown when divided by zero.

TypeError

This error is mainly related to the scalar type declaration in PHP 7. This error is displayed when you create a function or variable of a specific data type and try to save values ​​for different data types.

ParseError

eval()This error is thrown when using

to insert a new line of code or using an external PHP file containing a syntax error.

AssertionError

This error is only thrown when the assertion in the assert() function fails. The php.ini and assert.exception instructions are required to be configured in zend.assertions to catch this error.

Summary

The Throwable interface and Error classes introduced in PHP 7 simplify exception handling and make handling various error types easier. When upgrading to PHP 7, be aware of naming issues with custom Error classes and be familiar with new errors and extended classes.

FAQs (FAQs)

• What are the main changes in PHP 7 exception handling? PHP 7 introduces the Throwable interface and Error class, and all errors can be treated as exceptions and caught with the try/catch block.

• Throwable How does the interface work? Throwable is the base interface for all exceptions, implemented by Exception and Error.

• Error What is the function of the class? Error Class is used to handle internal PHP errors.

• How to handle exceptions in PHP 7? Use the try/catch block to capture Throwable, Exception and Error objects.

• What is the difference between

  Exception and Error? Exception for traditional exceptions, Error for internal PHP errors.

• How to throw an exception in PHP 7? Use the throw keyword.

• How to create a custom exception in PHP 7? Extend Exception Class.

• finally What is the function of keywords? The code in the finally block will be executed regardless of whether the exception is thrown or not.

• How to re-throw an exception in PHP 7? Use the catch keyword in the throw block.

• How to handle multiple exceptions in PHP 7? Include multiple try/catch blocks in the catch statement.

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