How to specify default types for parameters in PHP functions

Specifying the default type of parameters for PHP functions can improve code readability, strengthen type checking, and provide automatic type conversion. This applies to PHP 7.0 and above, the syntax is: function funcName(type $paramName, type $paramName2): type { // code body}, which allows specifying a default type, for example: function toUpperCase(string $name): string { // code body }, this will force the passing of string parameters to prevent type incompatibility warnings. Optional parameters can also use default type hints, such as: function greet(string $name, int $age = 0): void { // Code body }.

Specify default types for parameters in PHP functions

Default type hints allow you to specify default types for parameters in PHP functions, This helps improve code readability and maintainability. It can also trigger warnings or errors in case of type incompatibility.

Syntax

function funcName(type $paramName, type $paramName2): type
{
    // 代码体
}

Practical example

The following function accepts a string parameter$name, and convert it to uppercase letters:

function toUpperCase(string $name): string
{
    return strtoupper($name);
}

Now it forces a string type argument to be passed. If any other type is passed, a type incompatibility warning will be triggered.

Optional parameters

Default type hints can also be used for optional parameters. The following functions have an optional $age parameter, which defaults to 0:

function greet(string $name, int $age = 0): void
{
    // 代码体
}

Advantages

is specified for the parameter The default type has the following advantages:

• Improving the readability of the code: You can see the parameter type of the function at a glance.
• Enhanced type checking: Prevents parameters of incompatible types from being passed to functions.
• Provide automatic type conversion: Default type hints can automatically convert compatible types to specified types.

Note

• Only available in PHP 7.0 and above.
• Type hints will not be enforced, but warnings or errors will be triggered.

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