What are the types of PHP function return values, and what are their respective usage scenarios?

PHP functions can return values ​​of various data types, including scalar types (bool, int, float, string, null), composite types (array, object) and special types (mixed, void). This determines the nature of the data returned by the function and the operations allowed. Scalar types are used for basic data processing, composite types are used for storing and processing complex data, and special types are used to represent unknown or variable return values ​​or no return value.

PHP function return value type

In PHP, functions can return values ​​of various data types. These value types determine the nature of the data returned by the function and the operations allowed. Let’s explore function return value types in PHP and their common usage scenarios:

1. Scalar types

Boolean value (true or false)Judgment condition, control flowIntegerMathematical calculation, loop CounterFloating point numberScientific calculation, economic dataStringText processing, user inputNull value represents a non-existent value or placeholder

Types	Description	Usage scenarios
##bool
int
float
string
null

2. Composite type

TypeDescriptionUsage scenario##arrayobject

Key-value pair collection	Storage related data and data structures
Customized data Type	Encapsulates data and methods, object-oriented programming

3. Special types

Type##mixedThe return value type is unknown or variablevoidUsed to perform actions or initialize##Practical case

Description	Usage scenario
Any type
No return value

Example 1: Return a Boolean value to determine the condition (bool

)

function is_odd($number) {
  return $number % 2 === 1;
}

if (is_odd(15)) {
  echo "15 是奇数";
}

Example 2: Mathematical calculations using floating point numbers (float

)

function calculate_area($radius) {
  return 3.14 * $radius ** 2;
}

$area = calculate_area(5);
echo "半径为 5 的圆的面积为 $area";

Example 3: Return an array to store related data (array

)

function get_student_data($id) {
  return [
    'name' => 'John Doe',
    'age' => 25,
    'address' => '123 Main Street'
  ];
}

$student_data = get_student_data(1);
echo "学生姓名：{$student_data['name']}";

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