In PHP, how do I check if a function exists?

Question

How can I check if the function my_function already exists in PHP?

Answer 1

Checking Multiple function_exists

$arrFun = array('fun1','fun2','fun3');
if(is_array($arrFun)){
  $arrMsg = array();
  foreach ($arrFun as $key => $value) {
    if(!function_exists($value)){
      $arrMsg[] = $value;
    }
  }
  foreach ($arrMsg as $key => $value) {
    echo "{$value} function does not exist 
";
  }
}
function fun1(){
}

Output

fun2 function does not exist 
fun3 function does not exist