How do PHP functions return references?

PHP functions can be externally modified by returning a variable reference by using & as the function parameter type declaration. The following are examples of modifying variables through pass by value and pass by reference: Pass by value: The variable value does not change Pass by reference: The variable value does change

PHP Function How to return a reference

PHP functions can allow code outside the function to modify the variable value by returning a variable reference. This can be achieved by using two symbols (&) for the function parameter type declaration.

Syntax:

function &getVariableReference(...$args) {
    // ...
    return $variable;
}

Practical case:

The following are examples of changing variables by value passing and reference passing:

Pass by value:

$x = 10;

function changeValue($value) {
    $value++;
}

changeValue($x);

echo $x; // 输出 10，变量值未更改

Pass by reference:

$x = 10;

function &changeValueReference(&$value) {
    $value++;
}

changeValueReference($x);

echo $x; // 输出 11，变量值已更改

Notes:

• Returning a reference allows external variables to be modified, which may lead to unintended consequences.
• Pass-by-reference should be used with caution and ensure that its behavior is clearly documented.
• Returning references may cause memory leaks and unpredictable behavior.
• Avoid returning references in class methods, as this may cause confusion in the object's life cycle.

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