smart_concrat_example.sol

gistfile1.txt

pragma solidity ^0.4.0;
contract Counter{
    uint public count=10;
    function inc(uint num) public returns (uint){
        return count+=num;
    }
}
contract CallCounter{
    uint public count=20;
    function callByAddr(address addr) public returns(uint){
        return Counter(addr).inc(2);
    }
}
contract CallCounterByCall{
    uint public count=20;
    function callByAddr(address addr) public returns(bool){
        bytes4 methodId=bytes4(keccak256("inc(uint256)"));
        return addr.call(methodId,2);
    }
}
contract CallCounterByDelegateCall{
    uint public number=20;
    function callByAddr(address addr) public returns(bool){
        bytes4 methodId=bytes4(keccak256("inc(uint256)"));
        return addr.delegatecall(methodId,2);
    }
}