Problem using return in php recursive function

<?php
function test($i){
$i-=4;
if($i<3){
return $i;
}else{
test($i);
 }
}
echotest(30);

Code analysis: If you don't run it, you probably won't think there is any problem with it. If you run it in time and find a problem, you may not know where the problem is. But in fact, there is a problem in the else of this function. The execution result in this code has no return value. So although the condition $i

<?php
//php recursive function
function test($i){
$i-=4;
if($i<3){
return $i ;
}else{
return test($i);//Add return to let the function return the value
}
}
echotest(30);

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