我正在构建一种ATM程序，您可以在其中使用功能来存入和提取余额。我首先注意到，第一次存款后，它可以正常工作，但是第二次使用存款后，它不会将其添加到当前余额中，而是之前的余额。
例如：
（第一次尝试）
*余额= 1000
*我存入500
*现在的余额= 1500
（第二次尝试）
*我存700
*余额现在是1700
它没有重置为 2200 ，而是重置为 1000 ，然后进行了第二次尝试，结果为 1700 。 谁能解释一下代码出了什么问题？我不仅愿意获得正确的代码，而且还愿意学习如何完成代码。
这是我对c ++的培训。
#include <iostream>
#include <cstdlib>
#include <string>
using namespace std;
int deposit(int x, int y)
{
int newbal = x + y;
return newbal;
}
int withdraw(int x, int y)
{
int newbal = x - y;
return newbal;
}
int main()
{
int menu;
int selection;
double x = 1000, y;
int trans;
char user[20], pass[20], pktc[3];
string newuser, newpass;
do{
system ("CLS");
cout << "Welcome To Bank" << endl;
cout << "[1] Register" << endl;
cout << "[2] Login" << endl;
cout << "[3] Exit" << endl;
cout << "\n\nEnter command: " <<endl;
cin >> menu;
switch(menu)
{
//----------------------------------------------------------------CASE 1------------------------------------------------------------------------------//
//----------------------------------------------------------------REGISTER----------------------------------------------------------------------------//
case 1:
system ("CLS");
cout << "<-------REGISTER------->\n\n";
cout << "Enter Name: ";
cin >> user;
newuser = user;
cout << "Enter Password: ";
cin >> pass;
newpass = pass;
cout <<"REGISTERED SUCCESSFULLY!" << endl;
cout <<"\n\nPress Any key to contniue" << endl;
cin >> pktc;
system ("CLS");
break;
//------------------------------------------------------------END OF REGISTER--------------------------------------------------------------------------//
//----------------------------------------------------------------CASE 2------------------------------------------------------------------------------//
//-----------------------------------------------------------------LOGIN------------------------------------------------------------------------------//
case 2:
system ("CLS");
cout << "<-------LOGIN------->\n\n";
cout << "Enter Username: ";
cin >> newuser;
cout << "Enter Password: ";
cin >> newpass;
if(newuser != user || newpass != pass)
{
//-------------------------------------------------------------FAILED LOGIN----------------------------------------------------------------------------//
cout << "\nInvalid account" << endl;
cout <<"\n\nPress Any key to contniue" << endl;
cin >> pktc;
system ("CLS");
}
else if (newuser == user || newpass == pass)
{
//----------------------------------------------------------------CASE 2.1------------------------------------------------------------------------------//
//------------------------------------------------------------SUCCESFULL LOGIN--------------------------------------------------------------------------//
system ("CLS");
cout << "\n\n<-------------------------------WELCOME------------------------------->\n\n" << endl;
cout<<"\nWelcome To Banco De Nelio";
cout<<"\nUSERNAME: "<< user << endl;
cout<<"\n\n TIP ATM MACHINE";
cout<<"\n 1. Balance";
cout<<"\n 2. Deposit";
cout<<"\n 3. Withdraw";
cout<<"\n 4. Exit";
do{
cout<<"\n\nChoose Transaction[1-3]:";
cin>>trans;
switch(trans)
{
//----------------------------------------------------------------ATM CASE 1------------------------------------------------------------------------------//
//--------------------------------------------------------------CHECK BALANCE--------------------------------------------------------------------------//
case 1:
system ("CLS");
cout << "\n\n<-------------------------------WELCOME------------------------------->\n\n" << endl;
cout<<"\nWelcome To Banco De Nelio";
cout<<"\nUSERNAME: "<< user << endl;
cout<<"\n\n TIP ATM MACHINE";
cout<<"\n 1. Balance";
cout<<"\n 2. Deposit";
cout<<"\n 3. Withdraw";
cout<<"\n 4. Exit";
cout<<"\n\nYour total balance is: "<< deposit(x, y) ;
break;
//----------------------------------------------------------------ATM CASE 2------------------------------------------------------------------------------//
//--------------------------------------------------------------BEFORE DEPOSIT--------------------------------------------------------------------------//
case 2:
system ("CLS");
cout << "\n\n<-------------------------------WELCOME------------------------------->\n\n" << endl;
cout<<"\nWelcome To Banco De Nelio";
cout<<"\nUSERNAME: "<< user << endl;
cout<<"\n\n TIP ATM MACHINE";
cout<<"\n 1. Balance";
cout<<"\n 2. Deposit";
cout<<"\n 3. Withdraw";
cout<<"\n 4. Exit";
cout<<"\n\nEnter the amount:" ;
cin>>y;
//--------------------------------------------------------------AFTER DEPOSIT--------------------------------------------------------------------------//
system ("CLS");
cout << "\n\n<-------------------------------WELCOME------------------------------->\n\n" << endl;
cout<<"\nWelcome To Banco De Nelio";
cout<<"\nUSERNAME: "<< user << endl;
cout<<"\n\n TIP ATM MACHINE";
cout<<"\n 1. Balance";
cout<<"\n 2. Deposit";
cout<<"\n 3. Withdraw";
cout<<"\n 4. Exit";
cout<<"\n\nYour total balance now is: " << deposit(x, y) <<endl;
break;
//----------------------------------------------------------------ATM CASE 3------------------------------------------------------------------------------//
//--------------------------------------------------------------WITHDRAW BALANCE--------------------------------------------------------------------------//
case 3:
cout<<"\nEnter the amount:" ;
cin>>y;
if ( y > x)
{
cout<<"\nYou cannot withdraw " << y;
cout<<" because the amount is higher than your balance" << endl;
break;
}
else
x = x - y;
cout<<"\nYour Total Balance is now " << withdraw(x, y) << endl;
break;
//----------------------------------------------------------------ATM CASE 4------------------------------------------------------------------------------//
//-------------------------------------------------------------------BACK--------------------------------------------------------------------------------//
case 4:
cout<<"\n\nThank You!" << endl;
break;
default:
cout<<"\nYou did not enter any valid number" << endl;
break;
}
}while (trans<=3);
}
break;
//----------------------------------------------------------------CASE 3------------------------------------------------------------------------------//
//-----------------------------------------------------------------EXIT-------------------------------------------------------------------------------//
case 3:
system ("CLS");
cout << "Thank you for using me!\n";
return 0;
//-------------------------------------------------------------END OF EXIT----------------------------------------------------------------------------//
}
}while (menu<=3);
}
我不确定这里的问题是功能还是switch语句中的冲突。 在此先感谢
编辑请先注册：）
答案 0 :(得分：2)
很难发现重要的部分，但是基本上您的问题可以归结为
int add(int x,int y) { return a+b; }
int sub(int x,int y) { return a-b; }
int main() {
int initial = 0;
// add 10 then subtract 5
std::cout << add(initial,10) << '\n'; // prints 10
std::cout << sub(initial,5) << '\n'; // prints -5
}
当您真正想要的是
int main() {
int initial = 0;
// add 10 then subtract 5 and update initial
initial = add(initial,10);
std::cout << initial << '\n';
initial = sub(initial,5);
std::cout << initial << '\n';
}
您的方法正确地计算了新的金额，但是当您调用这些方法时，您将忽略返回值，而只想更新一些变量。
其他一些建议（以随机顺序）：
x和y没有传达任何含义，请将int deposit(int current_balance, int amount)与int deposit(int x,int y) std::endl结束行并刷新时，不要使用std::endl，这在大多数情况下不是您想要的），改为使用\n using namespace std;。它不会对您当前的代码造成很大的伤害，但是请阅读here为什么您永远不要在标头中使用它，并且最好不要从一开始就习惯坏习惯。