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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.
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## 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;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; }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;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; echo "b"; ?>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"; ?>b.php is as follows:
<?php echo "b"; exit; // 结束整个当前脚本 ?>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);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 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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