// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.4.16 <0.8.0;
// pragma solidity ^ 0.4.0;
contract FunReturn{
    function returnTest() public pure returns(uint num1){
        uint a = 10;
        return a;
    }
    function returnTest2() public pure returns(uint num1){
        num1 = 100;
    }
    // 返回10
    // 既有命名返回值 ，又有return, 以return的结果为准
    function returnTest3() public pure returns(uint num1){
        uint a = 10;
        num1 = 100;
        return a;
    }
    // 会进行类型轩换，将1转为uint
    function returnTest4() public pure returns(uint ){
        return 1;
    }
    // 可有以多个返回值
    function returnTest5(uint a, uint b) public pure returns(uint, uint){
        return (a + b, a * b);
    }
    // 多返回值的接收
    function getReturn() public pure{
        uint a;
        uint b;
        (a, b) = returnTest5(1, 2);
        (uint x, uint y) = returnTest5(10, 20);
        require(x > 0);
        require(y > 0);
        (, b) = returnTest5(1, 2);
    }
    function swap(uint a, uint b) internal pure returns(uint, uint){
        return (b,a);
    }
}