[solidity] mapping/array (feat.솔리디티깨부수기)

1. mapping

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;

//키를알면 값을 바로 뽑아서 쓸 수 있는데, length는 구할 수 없다!
contract lec13 {
    mapping(uint256=>uint256) private ageList;
    function setAgeList(uint256 _index, uint256 _age) public {
        ageList[_index] = _age;
    }
    function getAge(uint256 _index) public view returns(uint256) {
        return ageList[_index];
    }
//------------------------------------------------
    mapping(string=>uint256) private priceList;
    function setPriceList(string memory _itemName, uint256 _price) public {
        priceList[_itemName] = _price;
    }
    function getPriceList(string memory _index) public view returns(uint256) { //🚧키값에 itemName을입력해야 값이나옴
        return priceList[_index];
    }
//------------------------------------------------
    mapping(uint256=>string) private nameList;
    function setNameList(uint _index, string memory _name) public {
        nameList[_index] = _name;
    }
    function getName(uint256 _index) public view returns(string memory) {
        return nameList[_index];
    }
}

 

 

2. array

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;

contract let14 {
    uint256[] public ageArray;
    uint256[10] public ageFixedSizeArray; //인덱스0~9까지만 입력가능
    string[] public nameArray = ["Kal", "Jhon", "Kerri"]; //기본3개고정 이후 추가됨

    function AgeLength() public view returns(uint256){
        return ageArray.length;
    }
    
    // 0 -> 50/ 1 ->70/ length : 2
    function AgePush(uint256 _age) public {
        ageArray.push(_age);
    }
    
    // 1 -> 70
    function AgeGet(uint256 _index) public view returns(uint256){
        return ageArray[_index];
    }
    
    //0 -> 50/ length : 1
    function AgePop() public {
        ageArray.pop();
    }
    
    // 0 -> 0, 1 -> 70/ length : 2 .. delete는 값만 삭제한다.
    function AgeDelete(uint256 _index) public {
        delete ageArray[_index];
    }
    
    // 0 -> 90/ 1 -> 70/ length : 2  .. index에3을넣으면 에러뱉(없으니까)
    function AgeChange(uint256 _index, uint256 _age) public {
        ageArray[_index] = _age;
    }

}

 

 

3. mapping과 array에 주의할점

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;

contract lec15 {
    uint256 num = 89;
    mapping(uint256 => uint256) numMap;
    uint256[] numArray;

    function changeNum(uint256 _num) public {
        num = _num;
    }

    function showNum() public view returns(uint256) {
        return num;
    }
//mapping
    function numMapAdd() public {
        numMap[0] = num;
    }

    function showNumMap() public view returns(uint256) {
        return numMap[0];
    }
//array
    function numArrayAdd() public {
        numArray.push(num);
    }

    function showNumArray() public view returns(uint256) {
        return numArray[numArray.length-1];
    }

}