Solidity数据类型有哪些

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4.5. 数据类型

4.5.1. 数值型

int/uint：变长的有符号或无符号整型。变量支持的步长以8递增，支持从uint8到uint256，以及int8到int256。需要注意的是，uint和int默认代表的是uint256和int256。

有符号整型能够表示负数的代价是其能够存储正数的范围的缩小，因为其约一半的数值范围要用来表示负数。如：uint8的存储范围为0 ~ 255，而int8的范围为-127 ~ 127

支持的运算符:

比较：<=，<，==，!=，>=，>，返回值为bool类型。

位运算符：&，|，（^异或），（~非）。

数学运算：+，-，一元运算+，*，/，（%求余），（**次方），（<<左移），（>>右移）。

小数由"."组成，在他的左边或右边至少要包含一个数字。如"1."，".1"，"1.3"均是有效的小数。

4.5.1.1. 加 +，减 -，乘 *，除 ／ 运算演示

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract Math {  function mul(int a, int b) public pure returns (int) {      int c = a * b;      return c;  }  function div(int a, int b) public pure  returns (int) {      int c = a / b;      return c;  }  function sub(int a, int b) public pure  returns (int) {            return a - b;  }  function add(int a, int b) public pure  returns (int) {      int c = a + b;      return c;  }}

4.5.1.2. 求余 %

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract Math {  function m(int a, int b) public pure returns (int) {      int c = a % b;      return c;  }}

4.5.1.3. 幂运算

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract Math {  function m(uint a, uint b) public pure returns (uint) {      uint c = a**b;      return c;  }}

4.5.1.4. 与 &，| 或，非 ～，^ 异或

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract Math {  function yu() public pure returns (uint) {      uint a = 3; // 0b0011      uint b = 4; // 0b0100          uint c = a & b; // 0b0000      return c; // 0  }  function huo() public pure returns (uint) {      uint a = 3; // 0b0011      uint b = 4; // 0b0100          uint c = a | b; // 0b0111      return c; // 7  }  function fei() public pure returns (uint8) {      uint8 a = 3; // 0b00000011      uint8 c = ~a; // 0b11111100      return c; // 0  }    function yihuo() public pure returns (uint) {      uint a = 3; // 0b0011      uint b = 4; // 0b0100          uint c = a ^ b; // 0b0111      return c; // 252  }}

4.5.1.5. 位移

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract Math {  function leftShift() public pure returns (uint8) {      uint8 a = 8; // 0b00001000      uint8 c = a << 2; // 0b00100000      return c; // 32  }  function rightShift() public pure returns (uint8) {      uint8 a = 8; // 0b00001000      uint8 c = a >> 2; // 0b00000010      return c; // 2  }}

a << n 表示a的二进制位向左移动n位，在保证位数没有溢出的情况下等价于 a乘以2的n次方。
a >> n 表示a的二进制位向右移动n位，在保证位数没有溢出的情况下等价于 a除以2的n次方。

4.5.2. 字符串

string 字符串类型，字符串可以通过""或者''来定义字符串的值

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract StringTest {    string name;        function StringTest() public{        name = "default";    }    function setName(string _name) public{        name = _name;    }    function getName() public view returns(string){        return name;    }}

4.5.2.1. 获取字符串长度

在 Solidity 中想获得字符串长度必须转成 bytes 类型然后使用 length 属性获得。bytes(string).length

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract StringTest {            string public name = "http://www.netkiller.cn";        function nameBytes() public constant returns (bytes) {                return bytes(name);    }        function nameLength() public constant returns (uint) {                return bytes(name).length;    }    function length(string _name) public pure returns (uint) {                return bytes(_name).length;    }    }

4.5.3. 布尔(Booleans)

bool: 可能的取值为常量值true和false。支持的运算符：

! 逻辑非&& 逻辑与|| 逻辑或== 等于!= 不等于bool a = true;bool b = !a;// a == b -> false// a != b -> true// a || b -> true// a && b -> false

4.5.4. 字节类型

bytes names = "netkiller"bytes9 _names = "netkiller";bytes(name)[0] = 0xFF;bytes memory _tmp = new bytes(3);_tmp[0] = 0x4e;_tmp[1] = 0x65;_tmp[2] = 0x6f;

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract BytesTest {        bytes names = "netkiller";        function get() public view returns (bytes) {                return names;    }    function getBytes2() public pure returns (bytes2) {        bytes9 _names = "netkiller";        return bytes2(_names);    }    function bytesToString() public constant returns (string) {                return string(names);    }       function copyBytes(bytes b) public pure returns (bytes) {              bytes memory tmp = new bytes(b.length);              for(uint i = 0; i < b.length; i++) {                      tmp[i] = b[i];       }              return tmp;    }        function bytesToString2() public pure returns (string) {        bytes memory _tmp = new bytes(3);        _tmp[0] = 0x4e;        _tmp[1] = 0x65;        _tmp[2] = 0x6f;        return string(_tmp);    }   }

.length可以动态修改字节数组的长度

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract BytesTest2 {        // 初始化一个两个字节空间的字节数组    bytes public array = new bytes(2);        // 设置修改字节数组的长度    function setLength(uint _len) public {        array.length = _len;    }        // 返回字节数组的长度    function getLength() constant public returns (uint) {        return array.length;    }        // 往字节数组中添加字节    function pushArray(byte _tmp) public{        array.push(_tmp);    }    }

4.5.5. 数组

//创建一个memory的数组        uint[] memory a = new uint[](7);                uint[] x = [uint(1), 3, 4];            bytes memory b = new bytes(10);

二维数组

uint [2][3] T = [[1,2],[3,4],[5,6]];

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract ArrayTest {        uint [] array = [1,2,3,4,5];        // 通过for循环计算数组内部的值的总和    function sum() constant public returns (uint) {        uint num = 0;        for(uint i = 0; i < array.length; i++) {            num = num + array[i];        }        return num;    }        function sumNumbers(uint[] _numbers) public pure returns (uint) {        uint num = 0;        for(uint i = 0; i < _numbers.length; i++) {            num = num + _numbers[i];        }        return num;    }    }

4.5.5.1. length

.length 属性是活动数组的尺寸

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract ArrayLength {        uint [] array = [1,2,3,4,5];        function getLength() public constant returns (uint) {                return array.length;    }    }

4.5.5.2. push() 方法

通过 push 可以向数组中添加数据

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract ArrayLength {        uint [] array = [1,2,3,4,5];        function pushArray() public {                array.push(6);    }        function getLength() public constant returns (uint) {                return array.length;    }    }

4.5.6. 枚举类型

State 就是一个自定义的整型，当枚举数不够多时，它默认的类型为uint8，当枚举数足够多时，它会自动变成uint16，枚举下标定义从左至右从零开始。

New=0, Pending=1, Done=2, Deleted=3

访问枚举方式 State.New 实际等于数字 0

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract EnumTest {    enum State { New, Pending, Done, Deleted }    State state = State.New;    function set(State _state) public {        state = _state;    }    function get() constant public returns (State) {        return state;    }}

枚举用来定义状态

pragma solidity ^0.4.0;contract Purchase {    enum State { Created, Locked, Inactive } // Enum}

4.5.7. 结构体

定义结构体

struct Voter {        uint weight; // weight is accumulated by delegation        bool voted;  // if true, that person already voted        address delegate; // person delegated to        uint vote;   // index of the voted proposal    }    // This is a type for a single proposal.    struct Proposal {        bytes32 name;   // short name (up to 32 bytes)        uint voteCount; // number of accumulated votes    }

演示例子

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract Students {        struct Person {        string name;        uint age;        uint class;            }    Person person = Person("Neo",18,1);    function getPerson() public view returns(string){        return person.name;    }}

4.5.8. address

address public minter;

下面是一个获得账号余额的例子。

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract AddressTest{        function getBalance(address _addr) public constant returns (uint){        return _addr.balance;    }}

4.5.8.1. payable

4.5.8.2. .value()

4.5.8.3. .gas()

4.5.9. mapping

mapping 就是图数据结构，由 key 和 value 组成。

pragma solidity ^0.4.20;//Author: netkiller //Home: http://www.netkiller.cncontract MappingExample {        mapping(uint => string) map;    function put(uint key, string value) public {        map[key] = value;    }        function get(uint key) constant public returns (string) {        return map[key];    }}

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