How to use php return-PHP Tutorial-php.cn

How to use php return

angryTom

Release： 2023-04-07 09:16:01

Original

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How to use php return

In most programming languages, the return keyword can return the execution result of a function. The usage of return in PHP is also similar. For beginners, master the usage of return in PHP. It is also the beginning of learning PHP.

Recommended tutorial: PHP video tutorial

## First of all, it means return; return() is a language structure Instead of a function, parentheses are only required if the argument contains an expression. Parentheses are usually not used when returning a variable, which can reduce the burden on PHP.

Basic usage:

a), return expression // Return an expression result

　b), return(expr) / / Function expression

c), return // Return directly, or return a null value

Note: It is best not to use return($val) way.

1. If return is executed, the content after the return statement will not be executed;

function add($a,$b){
 return $a+$b;
 return $a*$b;
}
$c = add(5,3);//得到的$c值可以用在程序的其他地方！
echo $c;

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Output result: 8, only $a $b will be executed , $a*$b is not executed.

2. Return can be a function return value or a null value, depending on the specific usage, for example:

function test($a){
if($a>10){
 return "a>10";
}else{
 return "a<10";
}
$b=45;
$c=$b-$a;
echo $c;
}

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In this example, when you When you call this function and give it any number, it will return a string. If you give it a number 9, it will output the string "a<10" and the code:

$b=45;
$c=$b-$a;
echo $c;

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will never be executed. .

3. Regarding return calls.

a.php is as follows:

<?php
include("b.php");
echo "a";
?>

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b.php is as follows:

<?php
    echo "b";
    return;
    echo "b";
?>

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Output result: ba. The statement after return in b.php is no longer executed, and the statement after include("b.php") in a.php is still executed.

a.php is as follows:

<?php
include("b.php");
echo "a";
?>

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b.php is as follows:

<?php
echo "b";
exit; // 结束整个当前脚本
?>

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Output result: b.

4. An important role of return: return value

Example 1:

function test(){
 $a=array(1,2);
 return $a;
}
$b=test();
print_r($b);

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Example 2:

function test(){
 $a=array(1,2);
}
$b=test();
print_r($b);

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Output results : Example 1 outputs normally, Example 2 output is empty. why?

Because if you don’t use return to return a value in the function rest(), there will only be a process in the function and no result to rest(). Of course, there will be no value output when the function is called. Of course, we can also write print_r($b) into test() and print directly in the function, but many times, we will call operations outside the function, so we need to use return to return a value to the outside.

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