What is the closure in php?

Closure function: Temporarily create a function without a name, often used as a callback function. In layman's terms: child functions can use local variables in the parent function. This behavior is called closure.

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1. Anonymous function assignment

　$demo=function($str){
　　　　echo $str;
　　}
　　$demo('hello,world');

2. Closures can inherit variables from the parent scope. Any variables of this type should be passed in using the use language structure.

　$message='hello';
　　$example=function() use ($message){
　　　　var_dump($message);
　　};
　　echo $example();

Result: hello;

$example=function() use (&$message){
　　　　var_dump($message);
　　}
　

Result: hello;

$message='world';
　　echo $example();

Result: world;

$example=function($arg) use ($message){
　　　　var_dump($arg.' '.$message);
　　}
　　$example('hello');

Result: hello world;

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