The use of return type declarations in php7 new features

Suddenly I feel that php is gradually moving towards a strongly typed language, which is more and more similar to java, c and other strongly typed languages. When using PHP7, you will find that PHP7 contains a new feature, namely return type declaration. A return type declaration specifies the type of value that a function should return. The available types are the same as those available in the parameter declaration.

1. Declarable types:

• Integer type int

• Floating point type float

• Boolean type bool

• String type string

• Interface type interfaces

• Array array

• Callable

2. Usage example:

<?php
declare(strict_types = 1);
function returnIntValue(int $value): int {
      return $value;
   }
   print(returnIntValue(5));   //输出为5
?>

<?php
//默认declare()处于强制模式下
function returnIntValue(int $value): int {
      return $value+10.5;
   }
   print(returnIntValue(5));   //输出为15 不会报错，声明为int 返回为float
?>

After all, it is still weakly typed language.

<?php
declare(strict_types=1);
function returnIntValue(int $value): int {
      return $value+10.5;
   }
   print(returnIntValue(5));   //会报错，因为在declare()处于严格模式下，声明为int 返回为float，二者类型不符
?>

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