Detailed interpretation of return usage in php

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, mastering the usage of return in PHP is also the beginning of learning PHP.

First of all, it means return; return() is a language construct rather than a function, and it only needs to be enclosed in parentheses when the parameter 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).

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;

Output result: 8, only $a+$b is 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;
}

In this example, when you call this function, and then give any number, it will return a string and the code:

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

will never be executed.

3. Regarding return calls.

a.php is as follows:

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

b.php is as follows:

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

Output result: ba.

a.php is as follows:

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

b.php is as follows:

<?php
echo "b";
exit; // 结束整个当前脚本
?>

Output result: a.

4. An important role of return: return value

Example 1:

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

Example 2:

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

Output results: Example 1 outputs normally, Example 2 output is empty. why? Because if you don't use return to return the value in the function rest(), there will only be a process in the function, but 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.

I hope this article will be helpful to everyone’s PHP programming design.