Similarities and differences between PHP functions and Flutter functions

The main differences between PHP and Flutter functions are declaration, syntax and return type. PHP functions use implicit return type conversion, while Flutter functions explicitly specify return types; PHP functions can specify optional parameters through ?, while Flutter functions use required and [] to specify required and optional parameters; PHP functions use = to pass naming Parameters, while Flutter functions use {} to specify named parameters.

Similarities and differences between PHP functions and Flutter functions

Declaration and syntax

PHP functions

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

Flutter function

int sum(int a, int b) => a + b;

Optional and named parameters

PHP function

function Yes Specify optional parameters via ? and set default values ​​via =. Named parameters are passed using =.

function sum($a, $b = 0) {
  return $a + $b;
}

sum(1); // 1
sum(1, 2); // 3

Flutter function

Flutter function uses required to specify required parameters, [] to specify optional parameters,{} Specify named parameters.

int sum(int a, {int b = 0}) => a + b;

sum(1); // 1
sum(1, 2); // 3

Return value type

PHP function

PHP function uses implicit return type conversion and returns null by default.

function add(int $a, int $b) {
  return $a + $b; // 返回 int 型
}

Flutter function

Flutter function explicitly specifies the return type.

int sum(int a, int b) => a + b;

Practical case

PHP

<?php
function get_username($id) {
  $db = connect_database();
  $result = $db->query("SELECT username FROM users WHERE id='$id'");
  if ($result->num_rows > 0) {
    return $result->fetch_assoc()['username'];
  } else {
    return null;
  }
}

$username = get_username(1);
echo $username; // "john"
?>

Flutter

String? getUsername(int id) {
  // 连接数据库并查询数据...
  // 实际实现省略
  // 假设返回的用户名为 "john"

  return "john";
}

void main() {
  String? username = getUsername(1);
  print(username); // "john"
}

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