如何检查 PHP function 参数值是否通过调用 function 设置或默认值

Question

I want to check if PHP functions parameter value set by calling function or its a default value

function our_round($value,$decimal=6){
   if($decimal == 6 && $value < 0){
     $decimal = 9; // default
   }

   if($decimal == 6 && && value < 0 && provided by calling function){
     // need this logic to code here.
     // keep 6 if 6 provided by provider
     $decimal  = 6;
   }

   return round($value,$decimal);
}

// calling
our_round(1.1234567); // decimal default value
our_round(1.1234567,2); // decimal value provided 
our_round(1.1234567,6); // decimal value provided 

When calling function pass 6 in decimal, i want to check if its default or provided? to do some logic.

Answer 1

You can check what values were provided using func_get_args() . However, I have to agree with the comments that such an approach makes no sense.

function func($a = 2) {
    var_dump($a, func_get_args());
}
func();

func_get_args() only returns arguments which were passed in when calling the function, not set by default values.

In your case, it would make more sense to make the second parameter nullable and then have the complex logic inside of the function's body.

function our_round(float $value, ?int $decimal = null) {
    if (null === $decimal && $value < 0) {
        $decimal = 9; // default
    } else {
        // need this logic to code here.
        // keep 6 if 6 provided by provider
        $decimal = 6;
    }

    return round($value, $decimal);
}

I would recommend taking a piece of paper and drow some kind of truth table of possible options. If you just want to assign a default value in a simple way you can use a ternary operator.

function our_round(float $value, ?int $decimal = null) {
    // assign default value
    $decimal ??= $value < 0 ? 9 : 6;

    return round($value, $decimal);
}