Structural components of PHP functions

PHP function consists of function declaration, parameters, return value, variable scope, etc.: The function starts with function, followed by the function name and parameters in parentheses. Parameters are passed to the function and used within the function body. Functions can use return to return a value. Variables declared within a function have local scope, while variables declared outside a function have global scope. Practical case: You can write a function to calculate the average of two numbers.

Structural components of PHP functions

Function declaration

The function starts with function Starts with the keyword, followed by the function name and parentheses. Function arguments can be contained within parentheses, separated by commas. The function body is enclosed in curly braces {}.

function greet($name) {
  echo "Hello, $name!";
}

Parameters

Parameters are the data passed to the function. Parameters are defined in the function declaration and used in the function body.

Return value

A function can use the return statement to return a value. If not returned explicitly, the function returns null.

function add($a, $b) {
  return $a + $b;
}

Variable scope

Variables declared inside a function have local scope and can only be accessed within the function. Variables declared outside a function have global scope and can be accessed both inside and outside the function.

$global_variable = "global";

function test() {
  $local_variable = "local";
  echo $global_variable; // 输出 "global"
  echo $local_variable; // 输出 "local"
}

Practical case: Calculate the average of two numbers

The following function calculates the average of two numbers:

function average($a, $b) {
  return ($a + $b) / 2;
}

$avg = average(10, 20);
echo "The average is: $avg"; // 输出 "The average is: 15"

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