Msg.value of solidity

It will change when sending money to the contract msg.value Value .msg.value The value of wei In units of , The value is for the contract wei The number of .

The following contract can be used for testing

pragma solidity ^0.4.23;

contract tx{
    
    
    uint256 value;
    
    constructor()public payable{
    
        value = msg.value;
    }
    
    function number()public view returns(uint256){
    
        return value;
    }
    
    function n()public payable returns(uint256){
    
        return msg.value;
    }
    
    
}