3_Bank_account.sol

pragma solidity >= 0.7.0;
// Write  a  smart  contract  on  a  test  network,  for  Bank  account  of  a  customer  for
  // following operations: Deposit money | Withdraw Money | Show balance
contract Bank{
    mapping(address => uint) public user_account;
    mapping(address => bool) public user_exist;

    function create_account() public payable returns(string memory){
        require(user_exist[msg.sender] == false, "Account Already created!");
        user_account[msg.sender] = msg.value;
        user_exist[msg.sender] = true;
        return "Account created";
    }

    function deposit(uint amount) public payable returns(string memory){
        require(user_exist[msg.sender] == true, "Account not created!");
        require(amount > 0, "Amount should be greater than 0");
        user_account[msg.sender] += amount;
        return "Amount deposisted sucessfully";
    }

    function withdraw(uint amount) public payable returns(string memory){
        require(user_exist[msg.sender] == true, "Account not created!");
        require(amount > 0, "Amount should be greater than 0");
        require(user_account[msg.sender] >= amount, "Amount is greater than money deposisted");
        user_account[msg.sender] -= amount;
        return "Amount withdrawn sucessfully";    
    }

    function account_balance() public view returns(uint){
        return user_account[msg.sender];
    }
    
    function account_exists() public view returns(bool){
        return user_exist[msg.sender];
    }

}