PHP：在另一个函数中为变量运行函数[关闭]

I wanna print it to:

abcblabla

function r($data){
    strtolower($data);
}

function x($print){
    echo "abc".r($print);
}

x("BLABLA");

Just add return in your r() function.

function r($data){
   return strtolower($data);
}

function x($print){
echo "abc".r($print);
}

x("BLABLA");

The r() function needs to return the data. You do this by using the return statement.

function r($data){
   return strtolower($data);
}

More info on return can be found here

you just need to return the variable ,you forget to return