如何在solidity 0.5.2版中调用另一个合约中的合约？答案

【问题标题】：How to Call contract inside another contarct in solidity version 0.5.2?如何在solidity 0.5.2版中调用另一个合约中的合约？
【发布时间】：2019-06-16 15:14:00
【问题描述】：

我使用的是solidity 0.5.2版

pragma solidity ^0.5.2;

contract CampaignFactory{
address[] public deployedCampaigns;

function createCampaign(uint minimum) public{
    address newCampaign  = new Campaign(minimum,msg.sender);  //Error 
//here!!!
    deployedCampaigns.push(newCampaign);
} 

function getDeployedCampaigns() public view returns(address[] memory){
    return deployedCampaigns;
}
}

我在分配调用 CampaignFactory 合约中的 Campaign 合约时遇到错误

TypeError: Type contract Campaign is not implicitly convertible to expected 
type address.        
address newCampaign  = new Campaign(minimum,msg.sender);

我有另一个名为 Campaign 的合同，我想在 CampaignFactory 中访问它。

contract Campaign{
//some variable declarations and some codes here......

我的构造函数如下

constructor (uint minimum,address creator) public{
    manager=creator;
    minimumContribution=minimum;

}

【问题讨论】：

标签： blockchain ethereum solidity smartcontracts remix

【解决方案1】：

你可以直接施放：

address newCampaign = address(new Campaign(minimum,msg.sender));

或者更好的是，停止使用address 并使用更具体的类型Campaign：

pragma solidity ^0.5.2;

contract CampaignFactory{
    Campaign[] public deployedCampaigns;

    function createCampaign(uint minimum) public {
        Campaign newCampaign = new Campaign(minimum, msg.sender);
        deployedCampaigns.push(newCampaign);
    } 

    function getDeployedCampaigns() public view returns(Campaign[] memory) {
        return deployedCampaigns;
    }
}

【讨论】：

成功了！谢谢@smarkx，我会记住你的建议。

【解决方案2】：

要从另一个合约调用现有合约，请在 cast 中传递合约地址

pragma solidity ^0.5.1;

contract D {
    uint x;
    constructor (uint a) public  {
        x = a;
    }
    function getX() public view returns(uint a)
    {
        return x;
    }
}

contract C {
//DAddress : is the exsiting contract instance address after deployment
    function getValue(address DAddress) public view returns(uint a){
        D d =D(DAddress);
        a=d.getX();
    }
}

【讨论】：