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The use of return type declarations in php7 new features

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Release: 2023-02-17 20:54:01
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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
?>
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<?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
?>
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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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