What is the relationship between the type of PHP function return value and efficiency?

PHP function return value type will affect efficiency. Primitive types (scalars) are more lightweight than object types, which require additional memory allocation. The efficiency of an array depends on size and element type. NULL is generally heavier than scalar types. The void method is used to control program flow, but is less readable. Scalar or object types return the corresponding value directly. Object types are more expensive to create than scalar types, and memory management and cache utilization also suffer.

The relationship between the type of PHP function return value and efficiency

Overview
In PHP , the return value type of a function will affect its execution efficiency. It's important to understand the impact of different types of return values ​​to help optimize code performance.

Basic types

• Scalar types (non-object): Includes integers, floating point numbers, strings and Boolean values. These types are generally lighter than object types because they do not require additional space to be allocated in memory.
• Object type: References an external object instance. They are heavier than scalar types because they require the memory address of the object to be stored.

Composite type

• Array: Stores a set of key-value pairs. The efficiency of an array depends on its size and element type.
• NULL: represents a null value. It is a valid type, but is generally heavier than a scalar type because it requires a special tag to be allocated in memory.

Instance method

• void: A method that does not return any value. This is often used for program flow control, but makes the code less readable.
• Scalar or object type: Returns the value of scalar or object type directly.

Efficiency impact

• Creation overhead: The creation overhead of object types is higher than that of scalar types, which will affect Efficiency of functions called involving large arrays or complex objects.
• Memory management: Object types require additional space to be allocated in memory, which increases the memory footprint and the burden on the garbage collector.
• Cache utilization: Values ​​of scalar types can be stored in the CPU cache, which can improve access speed.

Practical case

The following code example illustrates the impact of different return value types on efficiency:

// 基本类型（整数）
function sum(int $a, int $b): int {
    return $a + $b;
}

// 对象类型（对象实例）
class MyClass {
    public $property;
}

function createObject(): MyClass {
    return new MyClass();
}

// 复合类型（数组）
function createArray(): array {
    return [1, 2, 3];
}

In the above example, sum() The function returns an integer, the createObject() function returns an object instance, the createArray() function returns an array. In terms of efficiency:

• sum() function is the fastest because its return value is a lightweight integer type. The
• createObject() function is slower than the sum() function because it requires creating a new object in memory.
• createArray() The efficiency of the function is somewhere in between because it returns a composite type, but its elements are simple integers.

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