take @ code:
$str = implode(', ', array_map(function($var1) use ($var2) { /* code */ }, $arr)); as see i've used use keyword import var2 in function. ok fine. can without use either. this:
$str = implode(', ', array_map(function($var1. $var2) { /* code */ }, $arr)); so when should use use ? has specific advantage?
the reason use use set variable value @ time of function definition rather when function called. example,
$var1 = 1; $var2 = 2; $fun1 = function($var1) use ($var2) { return $var1 + $var2; }; $fun2 = function($var1, $var2) { return $var1 + $var2; }; echo $fun1(3); // prints 5 echo $fun2(3,4); // prints 7 