contract Owner {

   modifier onlyOwner {

      require(msg.sender == owner);

      _;

   }

   modifier costs(uint price) {

      if (msg.value >= price) {

         _;

      }

   }

}

//Modifiers are code that can be run before and / or after a function call.

 //create modifier so the only person who can call the contract is the owner

    modifier onlyOwner{

        require(msg.sender == owner);

        _;

    }

​

  //create modifier so that we only allocate funds if friend's grandpa deceased

    modifier mustBeDeceased{

        require(deceased == true);

        _;

    }

modifier onlyOwner {

      require(msg.sender == owner);

      _;

  //Use _ after the last require statement

   }

Solidity basic definition for beginners like me.

Modifiers are code that can be run before and / or after a function call.

​

Modifiers can be used to:

​

Restrict access

Validate inputs

Guard against reentrancy hack