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Similarities and differences between PHP functions and Flutter functions

王林
王林Original
2024-04-24 13:12:01762browse

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.

PHP 函数与 Flutter 函数的异同

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

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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