declare(strict_type=1); is the strict type checking mode introduced in php7Specification syntax
When single filestrict_typesWhere should be written
Basic syntax
<?php
function add(int $a, int $b): int
{
return $a + $b;
}
var_dump(add(1.0, 2.0));When executing independently in this state, outputint (3)
What we provide is the double type, but php7 can handle it well, and php5There is no difference in the times
The following changes were made
<?php
declare(strict_types=1); //加入这句
function add(int $a, int $b): int
{
return $a + $b;
}
var_dump(add(1.0, 2.0));TypeError occurred, as follows
PHP Fatal error: Uncaught TypeError: Argument 1 passed to add() must be of
the type integer, float given, called in /Users/hiraku/sandbox/stricttypes/A.php on line 9 and defined in
/Users/hiraku/sandbox/stricttypes/A.php:4
Stack trace:
#0 /Users/hiraku/sandbox/stricttypes/A.php(9): add(1, 2)
#1 {main}
thrown in /Users/hiraku/sandbox/stricttypes/A.php on line 4strict_typesCannot be written in the middle of the script
declareThe syntax cannot be written in the middle of the script. The following writing is wrong
<?php
function add(int $a, int $b): int
{
return $a + $b;
}
declare(strict_types=1);
var_dump(add(1.0, 2.0));The following error occurs
PHP Fatal error: strict_types declaration must be the very first statement in the script in /Users/hiraku/sandbox/stricttypes/A.php on line 7
Fatal error is generated, this is not even Throwable, but an error generated during the compilation process
Similarly, the following syntax cannot be used in positions similar to the above examples
<?php
declare(strict_types=1) {
//...
}PHP Fatal error: strict_types declaration must not use block mode in /Users/hiraku/sandbox/stricttypes/A.php on line 2
When there are two filesstrict_typesHow does it work
The following code
A.phpscript Declaring strict mode at the beginning
A.php脚本
<?php
declare(strict_types=1);
function add(int $a, int $b): int
{
return $a + $b;
}A.php is B.php filerequire, as follows
B.php脚本 <?php require 'A.php'; var_dump(add(1.0, 2.0)); //注意这里键入的是1.0和2.0浮点数,而A.php声明需要int
execution results
$ php B.php int(3)
What!!!! It can be executed without error!!!!!
It turns out that B.php did not declare strict_types , so for B script, it is the default loose mode
That is to say, for strict_types there is the following behavior
- No matter what , there will be no difference in the strict mode behavior when the function is defined
- There will be differences in the strict mode when the function is executed
declare(strict_types=1);'s syntax itself is completed in theA.phpfile, and isB.phpfilerequire, andB.phpdoes not define strict mode, so the file (B.php) that executesrequirewill not become strict mode
The above explanation is as shown in the following code. In theory, the strict mode of the A.php file has been turned off, but only the B.php file has set declare (strict_types=1);, then even if A.php does not set strict mode, A.php is referenced by B.php, Just use strict mode for A.php
A.php
<?php
function add(int $a, int $b): int
{
return $a + $b;
}B.php <?php declare(strict_types=1); require 'A.php'; var_dump(add(1.0, 2.0));
$ php B.php PHP Fatal error: Uncaught TypeError: Argument 1 passed to add() must be of the type integer, float given, called in /Users/hiraku/sandbox/stricttypes/B.php on line 4 and defined in /Users/hiraku/sandbox/stricttypes/A.php:2
When there are three files, the role of declare(strict_types=1);
is in the function definition part Use declare(strict_types=1);
to add another require and try nesting three files
C.php → B.php → A.php
C.php <?php require_once 'B.php'; var_dump(add(1.0, 2.0)); var_dump(add2(1.0, 2.0));
B.php
<?php
declare(strict_types=1); //在函数定义部分声明
require_once 'A.php';
function add2($a, $b)
{
return add($a, $b);
}A.php
<?php
function add(int $a, int $b): int
{
return $a + $b;
}The execution result is as follows
$ php C.php int(3) PHP Fatal error: Uncaught TypeError: Argument 1 passed to add() must be of the type integer, float given, called in /Users/hiraku/sandbox/stricttypes/B.php on line 7 and defined in /Users/hiraku/sandbox/stricttypes/A.php:2
- ##var_dump(add(1.0, 2.0));
Can be executed correctly - var_dump(add2 (1.0, 2.0));
Produces TypeError
declare(strict_types=1);will change as follows
- The file that defines the function itself will not produce effects Calling other functions in the defined function, strict mode can produce effects (
- B.php
usesstrict_types= 1, at the same timeB.phpcallsA.php, soA.phpcan work)
C.php <?php declare(strict_types=1); //主体部分声明 require_once 'B.php'; var_dump(add2(1.0, 2.0));Copy after loginB.php <?php require_once 'A.php'; function add2($a, $b) { return add($a, $b); }Copy after loginA.php <?php function add(int $a, int $b): int { return $a + $b; }Copy after loginCopy after loginCopy after login$ php C.php int(3)Copy after login
- strict_types=1 is used in C.php, so add2(1.0,2.0) is executed in strict mode, But since no variables are declared, there is no effectOn the other hand, B.php with add2() definition is in non-strict mode
declare is written. Other functions called in the file (functions in other files) will also be affected.
declare is written, all the code in that file needs to be checked, even if the code in it comes from other files. At the same time, even if the file that needs to be checked is also called by other files, the file that needs to be checked will not be changed. Fact
Foo.php
<?php
// 这个文件的strict有效
declare(strict_types=1);
class Foo
{
private $bar;
public function __construct()
{
$this->bar = new Bar; // 执行严格模式
}
public function aaa()
{
$this->bar->aaa(); // 执行严格模式
}
}
