What is the difference between php7 and php8

Main differences between PHP 8 and PHP 7 include: property type declarations, union types, null coalescing operator, JIT compiler, optimized memory management, preloading capabilities, Enum types, improved exception handling and modern syntax .

The main difference between PHP 7 and PHP 8

PHP 8 is a major version upgrade of PHP 7, bringing Many new features and performance improvements. Here are the main differences between PHP 7 and PHP 8:

Language features:

• Attribute type declaration:Introduced in PHP 8 Property type declaration allows specifying types for object properties.
• Union type:PHP 8 supports union types, allowing variables to have multiple types at the same time.
• null coalescing operator:PHP 8 introduces the new "??=" operator, which is used to determine whether a variable is null and assign a default value.

Performance improvement:

• JIT compiler:PHP 8 integrates a JIT (just-in-time compiler) compiler, Can improve execution speed.
• Optimize memory management:PHP 8 improves memory management and reduces the overhead of memory allocation and release.
• Preloading function:PHP 8 adds a preloading function, allowing commonly used functions and classes to be loaded before script execution, thereby improving response speed.

Other improvements:

• Enum type:PHP 8 introduced the Enum type, providing a safe and secure type Safe way to represent enumeration values.
• Improved exception handling:PHP 8 has improved exception handling, introducing new exception types and new syntax for throwing exceptions.
• Modern syntax:PHP 8 removes outdated syntax features and introduces a more concise and modern syntax.

Example:

Property type declaration in PHP 7:

// 无法指定类型 class Foo { public $name; }

In PHP 8 Property type declaration for:

// 指定类型为字符串 class Foo { public string $name; }

Union type in PHP 7:

// 不可行，PHP 7 不支持联合类型 function foo($bar) {}

Union type in PHP 8:

// 指定联合类型为字符串或整数 function foo(string|int $bar) {}

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