How to determine the type of a PHP function's return value based on its signature?

By checking the function signature, we can determine its return value type: The @return tag indicates the return value type. Type hints specify the type. Class documentation provides return value information.

How to determine the type of return value of a PHP function based on its signature

In PHP, a function signature consists of its name and parameters List composition. By inspecting the function signature, we can infer the type of its return value. Here's how to do it:

1. Use the @return tag

@return tag for documentation The return value type of the function. It is placed in the comment block before the function definition. For example:

/**
 * 获取用户的名称
 *
 * @return string 用户的名称
 */
function getUserName(): string {}

In this case, the @return tag clearly indicates that the function returns a value of type string.

2. Use type hints

PHP 7 introduced type hints, allowing us to specify types on function parameters and return value types. For example:

function getUserName(): string {}

This tells the PHP parser that the function returns a value of type string.

3. Check the class documentation

For built-in PHP functions or user-defined class methods, we can find the return value type information in its class documentation. For example, we can use the getdoc command to get the documentation for the array_merge function:

$ getdoc -j array_merge | jq '.tags[]'
"return"

This indicates that the array_merge function returns a value of type array.

Practical case

Suppose we have the following function:

function calculateArea($length, $width) {
  return $length * $width;
}

We can use the following method to determine the type of its return value:

Method 1: Using the @return tag

Add a comment block before the function definition containing the @return tag:

/**
 * 计算矩形的面积
 *
 * @param float $length 矩形的长度
 * @param float $width 矩形的宽度
 * @return float 矩形的面积
 */
function calculateArea($length, $width) {
  return $length * $width;
}

Method 2: Use type hints

Use type hints in function definition:

function calculateArea(float $length, float $width): float {
  return $length * $width;
}

Using any of these methods, we can easily Determine the return value type of the function.

The above is the detailed content of How to determine the type of a PHP function's return value based on its signature?. For more information, please follow other related articles on the PHP Chinese website!