区块链学堂（22）：String 数组类型-蒲公英云

区块链学堂（22）：String 数组类型

String类型的官方定义

String literals are written with either double or single-quotes (“foo” or ‘bar’). They do not imply trailing zeroes as in C; “foo”` represents three bytes not four. As with integer literals, their type can vary, but they are implicitly convertible to bytes1, …, bytes32, if they fit, to bytes and to string.

String literals support escape characters, such as \n, \xNN and \uNNNN. \xNN takes a hex value and inserts the appropriate byte, while \uNNNN takes a Unicode codepoint and inserts an UTF-8 sequence. 引用自here

String数组类型定义

string[] strArr

String数组的增删改查

Step 1: 首先撰写一个String数组的contract和构造函数

pragma solidity 0.4.10;
contract Demo {
  string[] public strArr;
  function Demo() {
      strArr.push("init");
  }
}

Step 2: 添加一个Add function

function Add(string str) {
      strArr.push(str);
  }

Step 3: 添加一个Update function

function Update(uint index, string str) {
      if (index > strArr.length-1) throw;
      strArr[index] = str;
  }

大家注意一下，如果index>strArr.length-1, 此时应抛出异常

Step 4: 添加一个ValueOf function

function ValueOf(uint index) returns (string str){
      if (index > strArr.length-1) throw;
      return strArr[index];
  }

Step 5: 添加一个DeleteAt function

function DeleteAt(uint index) {

    uint len = strArr.length;
    if (index > len-1) throw;
    for (uint i = index; i<len-1; i++) {
        strArr[i] = strArr[i+1];
    }
    delete strArr[len-1];
    strArr.length--;
}