ethereum(以太坊)(十)--函数修饰符

pragma solidity ^0.4.0;

contract modifierTest{
    uint public v1;
    uint constant v2 =10;
    //uint constant v3; Uninitialized "constant" variable
    
    string public v4='test1';
    string constant v5='test2';
    //string constant v6;Uninitialized "constant" variable
    
    function f() public{
        v1 = 10;
        //v2 = 20;Cannot assign to a constant variable
        
        v4 = 'vtesst';
        //v5 = 'vtest2';Cannot assign to a constant variable
    }
    
    struct test{
        string name;
        uint _sex;
    }
    
    //test constant test1; constant 仅可以修饰值类型,无法修饰引用类型(string除外)
    function set() constant public{ //被修饰的函数内,状态变量无法被改变
        v1 =100;
    }
    
    //告诉编译器，函数不改变/不读取状态变量，这样函数执行就可以不消耗gas了，因为不需要矿工来验证
    
    // 1.view 仅可以修饰函数
    // 2.在该函数内,仅可以对storage类型的变量进行读取,无法修改
    
    address owner;
    function setview(address add) view public { 
        owner =  add;
    }
    
    function getadd()returns(address){
        return owner;
    }

    
    // 1.pure 仅可以修饰函数
    // 2.在函数内,无法读写状态变量--
}