problem with new syntax

[startgeek]

there are couple of problems
first: version of pragma should change to pragma solidity >=0.4.0 <0.6.0;
second : using same name for constructor function as contract name is deprecated
third : this keyword always raise a error in tokensale.sol I'm not sure why
by the way thanks for great videos

[mmcc1]

this should be address(this)

[gabefighter99]

Also the tests that contain indexOf are failing. Is indexOf no longer a function? How to replace?