How does the parameter passing method of PHP functions handle large-scale data passing?

The function parameter passing method is crucial for processing large-scale data. PHP provides three methods: 1) Pass by value: a copy is passed to the function without affecting the original variable; 2) Pass by address: a reference to the original variable is passed, and modifications in the function will affect the original variable; 3) Pass by reference: mandatory parameters Passed as a reference, even if a primitive type is passed in.

PHP function parameter passing method: large-scale data transfer optimization

In PHP, the function parameter passing method is very important for processing large-scale data Data at scale is critical. PHP provides three parameter passing methods:

1. Pass-by-value

Pass a copy to the function. If you modify the copy in the function, the original variable is not affected. Applies to basic types (integers, floats, booleans, strings) and immutable objects.

function sum($num) {
  $num = $num * 2;
}

$num = 10;
sum($num);
echo $num; // 输出：10

2. Pass-by-reference

Pass a reference to the original variable. If you modify a variable within a function, the original variable will also be modified.

function sum(&$num) {
  $num = $num * 2;
}

$num = 10;
sum($num);
echo $num; // 输出：20

3. Pass-by-reference

is similar to pass-by-reference, but forces the parameters to be passed as references, even if the passed-in The same goes for basic types.

function sum(int &$num) {
  $num = $num * 2;
}

$num = 10;
sum(10); // 报错：只能传递变量

Practical case

When dealing with large-scale arrays, you usually choosepass by reference because:

• It allows direct manipulation of the original array transferred to the function to improve operating efficiency.
• Avoid the memory overhead caused by copying large arrays.

function processArray(array &$array) {
  // 在这里修改数组元素
}

$array = range(1, 100000); // 生成一个包含 100000 个元素的数组
processArray($array);

Note

• Only references can be used as output parameters. If a function needs to modify data internally and return the modified result, the original variable should be passed as a reference and the modified reference should be returned.
• Avoid abuse of pass-by-reference. Use only if you really need to modify variables outside the function.
• Focus on performance. In practical applications, it is crucial to choose the most appropriate parameter passing method based on data size and operation type.

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