Ethereum Cookbook

How to do it…

1. Contracts can have a cap to restrict the amount that can be raised through the crowdsale. Create a variable to store the cap restriction:

uint256 public cap;

2. The value is assigned through the constructor. Add the initialization to the constructor along with the rate, wallet, and token:

constructor(uint256 _cap, ....)     public {    // Other validations and assignment    require(_cap > 0);     cap = _cap;}

3. During the token purchase operation, add an additional condition to verify the cap:

function buyTokens(address _investor) public payable {    require(weiRaised.add(_weiAmount) <= cap);    //..}

4. Create a read-only function that can be used to check whether the cap has been reached. It returns true or false:

function capReached() public ...