如何检查常量是否在函数内部定义-PHP

Question

I am trying to make a small PHP function which can check if a constant is defined, and if so, echo it, and if not, echo space or nothing.

Right now, the if(defined() part is not working, because the constant is being transferred to a variable inside the function.

function getConstant($constant) {  
  if(defined($constant)) {
    echo constant($constant);
  } else {
    echo '';
  }
}

The echo constant($constant) part is working fine, but I cannot check if the constant is actually defined because it is a variable now.

I cannot seem to find a solution for it

Answer 1

public static function isConstants($constant) {
    $oClass = new ReflectionClass(__CLASS__);
    $allConstants = $oClass->getConstants();
    if (isset($allConstants[$constant])) {
       echo $allConstants[$constant];
    } else {
       echo '';
    }
}