Eval() in PHP and Javascript

Use of eval() function, Error handling of eval function

The eval is used to execute the a string value. If you want to execute a string value like 
an arithmetic string eg: "4+3*6", then you can use the eval function to calculate the string.

In php and javascript you can use the eval() function.
Javascript:
===========
The eval() function will leads to many syntax error whenever the statement inside the function is not executable.
So you can use the try{}catch{} method.

var statement = "4+3*6";
try{
  var calculated = eval(statement);
}catch(e){
  
}

PHP
=====
PHP will also produce parse error while running the eval. In php 7 it will thrown an exeption. 
So we can use the try{}catch{} method to catch the exception and it wont halt the execution.

But in php below 7 it will create parse error which will stop the php execution. 
So before php 7 you can use any other method to solve the parse error. Please refer.
https://stackoverflow.com/questions/3223899/php-eval-and-capturing-errors-as-much-as-possible

You can write a function to check a ,valid eval statement. like below.
function is_valid_eval_code($code){
  return @eval($code . "; return true;");
}

This will return true if eval code is valid one.

eg:
$code = "4*3*6-4";
if(phpversion() >= 7){
    try {
      $value = eval("return $code;");
    } catch (ParseError $e) {
      echo $e->getMessage();
    }
}else{
   $value = eval("return $code;")
}