What is the difference between PHP functions and Kotlin functions?

The difference between PHP and Kotlin functions: PHP function return type is optional, parameters are passed by value, supports variable number of parameters, can be declared as a static function, and anonymous functions are allowed; Kotlin function return type is clear, and parameters can be passed by value or reference , does not support variable number of parameters, only member functions or top-level functions, and can only use lambda expressions to define anonymous functions.

The difference between PHP functions and Kotlin functions

PHP and Kotlin are both popular programming languages. They have different syntax and semantics. There are some similarities. However, there are also significant differences in how functions operate.

PHP function

• Return type is optional (default is void)
• Parameter passing is passed by value
• Supported A variable number of arguments (using the...$args syntax)
• can be declared as a static function (using the static keyword)
• can be an anonymous function (using the function keyword)

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

// 调用函数
greet("John");

Kotlin functions

• The return type must be explicitly specified
• Parameter passing is passed by value (default), or by reference (using out or inout keyword)
• Unable to declare variable number of parameters
• Can only be declared as a member function (belonging to a class or object) or a top-level function
• Can be defined using lambda expressions Anonymous function

fun greet(name: String) {
    println("Hello, $name!")
}

// 调用函数
greet("Mary")

Practical case

Suppose we have a function that calculates the sum of two numbers.

PHP

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

Kotlin

fun sum(a: Int, b: Int): Int {
    return a + b
}

While these two functions are functionally similar, their key differences are Relies on:

• Return type: The return type of a PHP function is void (if not explicitly specified), while the return type of a Kotlin function must be explicitly declared.
• Parameter passing: Parameters in PHP are passed by value, while in Kotlin parameters can be passed by value or by reference.
• Anonymous functions: PHP allows anonymous functions, while Kotlin can only define anonymous functions using lambda expressions.

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