PHP 动态调用函数

Question

I am writing a program in PHP to assign a function name to a variable and invoke it dynamically. I have the code below, when I run the code for addition, it is showing answers for all.

function multiply($val1, $val2)
{
  $mul = $val1 * $val2;
  echo $mul;
}

function divide($val1, $val2)
{
  $div = $val1 / $val2;
  echo $div;
 }

$func = plus($_POST['val1'], $_POST['val2']);
$func = minus($_POST['val1'],$_POST['val2']);
$func = multiply($_POST['val1'],$_POST['val2']);
$func = divide($_POST['val1'],$_POST['val2']);

please help.

Answer 1

With your suggested code you do not create 4 variables to be called dynamically, instead you call the 4 functions plus, minus, multiply and divide. Those functins generated the output, just as you implemented them to do. $func is simply always replaced by the return value of those functions.

Instead you should try something like this if you really have to use dynamic function calls:

call_user_func($_POST['operation'],$_POST['val1'],$_POST['val2']);

Note that for production you really should validate the post variables values.

Answer 2

Please have a look on how to use variable functions here and check back with the complete code you`ve tried.

Maybe you`re trying to to something like this:

function add($one, $two)
{
   return $one + $two;
}

$funcname = "foo";
echo $funcname(1, 4);

Answer 3

You could also implement your functions as a closure and pass around that closure. If passing around a function is what you want.

$divide = function($val1, $val2) {
    $div = $val1 / $val2;
    echo $div;
};

$divide($_POST['val1'], $_POST['val2']);
other_function($divide, $param, $otherParam); // you could use the closure $divide inside this function.

But please don't forget to escape the user input you're using for your script.

Answer 4

Here's what you can try and make it fit in your need.

function user_selection($operation,$op1,$op2){
   switch ($operation){
    case '+':
        return $op1 + $op2;
        break;
    case '-':
        return $op1 - $op2;
        break;
    case '*':
        return $op1 * $op2;
        break;          
    case '/':
        return $op1 / $op2;
        break;  
    }

}

and to call above function, you can put

  $functionName = 'user_selection';
  echo $functionName('+',1,2);

You can do different things by changing arguments,operations etc etc. For better understanding how this thing work look php manual for variable functions