Introduction

In this smart contract, we'll discuss the smart contracts. 

In my previous, I created a contract to send the amount and check the balance. My problem is I check any address balance not only for the msg.sender. 

Then what do we do? 

we create a function and inside this function passed one parameter and the data type is the address type. 

 function checkBalance(address _add) override public view returns(uint){
        return balances[_add];
    }

 In mapping, they check the address value in which uint is stored. 

Code

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.4.5 <0.9.0;

interface ERC {
    
    function transfer(address receiver, uint amount) external returns(bool);
    function checkBalance(address add) external returns(uint);
    
    event Transfer(address from, address to, uint value) ;
    
}

contract MyContract is ERC{
    
    uint totalSupply = 1000;
    address owner;
   
    
    mapping ( address => uint ) balances;
    
    constructor(){
        owner = msg.sender;
        balances[owner] = totalSupply;
    }
    
    function transfer(address _to, uint _value)  override public returns(bool){
        require( balances[owner] >= _value, "Not enough amount" );
        balances[owner] -= _value;
        balances[_to] += _value;
        emit Transfer(msg.sender, _to, _value);
        return true;
     
    }
    
    function checkBalance(address _add) override public view returns(uint){
        return balances[_add];
    }
    
}