在本文中，任务是使用C++中的文件处理功能来实现具有添加，删除，搜索和更新用户之类功能的ATM。
文件处理：
- 文件处理用于将程序的输出存储在文件中。
- 在C++中，文件使用fstream头文件中可用的三个类fstream ， ifstream和ofstream进行文件处理。
一些重要说明：
- 管理员登录的密码是1234 。
- 最初，该文件为空，请确保首先以admin身份登录并添加用户，然后以用户身份登录。
方法：
- 选择用户类型并输入密码。
- 在给定的菜单中，选择基本操作，然后在操作中输入详细信息，例如添加，删除，搜索和更新用户。
- 完成所有功能和操作后，退出ATM系统。
- 所有文件操作都在名为aaa.txt的文件中完成，在该文件中，数据是使用ofstream模式写入的，并且可以使用ifstream模式读取。
- 之后，必须使用
.close() 关闭文件。
下面是上述方法的实现：
C++
// C++ code to implement an ATM and
// its basic functions
#include
#include
#include
#include
#include
using namespace std;
// Class ATM to get user details
class atm {
private:
char username[30];
int password;
int balance;
public:
char* usernames(void)
{
// Return username
return the username;
}
int passwords(void)
{
// Return the password
return password;
}
// Function to get the data
void getData(void)
{
cin.ignore(
numeric_limits::max(),
'\n');
cout << "\nEnter username:";
cin.getline(username, 30);
cout << "\nEnter 4-digit "
<< "password:";
cin >> password;
cin.ignore(
numeric_limits::max(),
'\n');
cout << "\nEnter initial"
<< " balance:";
cin >> balance;
cin.ignore(
numeric_limits::max(),
'\n');
}
// Function displaying the data
void showData(void)
{
cout << "Username:" << username
<< ", Password:" << password
<< ", Balance:" << balance
<< endl;
}
// Member Functions
int adduser();
int viewallusers();
int deleteuser(char*);
void updateuserasdeposit(char*);
void updateuseraswithdraw(char*);
int searchspecificuser(char*, int);
int searchallusertodisplay(char*);
};
// Function to implement functionality
// of ATM User
void atmUser()
{
atm a;
char uname[30];
int pass, ch, ch1, ch2, found = 0;
mainmenu:
// System("cls");
cout << "\nWelcome to GeeksforGeeks ATM";
cout << "\nLogin as :\n1. Admin\n2."
<< " User\n3. "
"Exit\nChoose one : ";
cin >> ch;
switch (ch) {
case 1:
rerun:
// System("cls");
cout << "\nEnter details to"
<< " login as Admin\n";
cout << "\nEnter password:";
cin >> pass;
if (pass == 1234) {
admin:
// System("cls");
cout << "\nWelcome to"
<< " Admin Menu";
cout << "\n1. Add User\n2."
<< " Delete User\n3. "
"View All User\n4. "
<< "Exit";
cout << "\nSelect one : ";
cin >> ch1;
switch (ch1) {
case 1:
a.adduser();
goto admin;
case 2:
cout << "\nEnter the "
<< "Username to be "
"deleted : ";
cin.ignore(
numeric_limits::max(),
'\n');
cin.getline(uname, 30);
a.deleteuser(uname);
goto admin;
case 3:
a.viewallusers();
// sleep(4);
goto admin;
case 4:
break;
}
}
else {
cout << "\nDetails are "
<< "incorrect ! Please"
" try again";
cin.get();
goto rerun;
}
goto mainmenu;
case 2:
// System("cls");
cout << "\n Enter details to"
<< " login as User\n";
cin.ignore(
numeric_limits::max(),
'\n');
cout << "Enter username:";
cin.getline(uname, 30);
cout << "\nEnter password:";
cin >> pass;
found = a.searchspecificuser(
uname, pass);
if (found) {
user:
// System("cls");
cout << "\nWelcome "
<< uname;
cout << "\nWelcome to"
<< " User Menu";
cout << "\n1. Deposit\n2."
<< " Withdraw\n3. View "
"Account\n4. "
<< "Exit\nEnter your choice:";
cin >> ch2;
switch (ch2) {
case 1:
a.updateuserasdeposit(uname);
goto user;
case 2:
a.updateuseraswithdraw(uname);
goto user;
case 3:
a.searchallusertodisplay(uname);
// sleep(4);
goto user;
case 4:
cout << "Thank you";
break;
}
}
else {
cout << "\nNo account found"
<< " with username "
":(\n\nHit ENTER to continue "
<< uname;
cin.get();
}
goto mainmenu;
case 3:
cout << "\nThankyou for "
<< "banking with "
<< "GeeksforGeeks";
cin.get();
break;
}
}
// Function to add user
int atm::adduser()
{
atm a;
ofstream file;
// Open file in write mode
file.open("aaa.txt",
ios::out | ios::app);
if (!file) {
cout << "Error in creating "
<< "file.." << endl;
return 0;
}
// Read from user
a.getData();
// Write into file
file.write((char*)&a, sizeof(a));
// Close the file
file.close();
return 0;
}
// View Users
int atm::viewallusers()
{
atm a;
ifstream file1;
// Open file in read mode
file1.open("aaa.txt", ios::in);
if (!file1) {
cout << "Error in opening file..";
return 0;
}
// Read data from file
file1.read((char*)&a, sizeof(a));
while (!file1.eof()) {
// Display data on monitor
a.showData();
file1.read((char*)&a, sizeof(a));
}
// Close the file
file1.close();
return 0;
}
// Function to delete the user
int atm::deleteuser(char* uname)
{
atm a;
fstream original, temp;
original.open("aaa.txt", ios::in);
if (!original) {
cout << "\nfile not found";
return 0;
}
else {
temp.open("temp.txt",
ios::out | ios::app);
original.read((char*)&a, sizeof(a));
// Till end of file is reached
while (!original.eof()) {
if (!strcmp(a.usernames(),
uname)) {
cout << "data found "
<< "and deleted\n"
<< a.username
<< "\n";
}
else {
temp.write((char*)&a,
sizeof(a));
}
original.read((char*)&a,
sizeof(a));
}
original.close();
temp.close();
remove("aaa.txt");
rename("temp.txt", "aaa.txt");
a.viewallusers();
}
return 0;
}
// Function to update user by
// depositing money
void atm::updateuserasdeposit(char* uname)
{
atm a;
fstream file, temp;
file.open("aaa.txt",
ios::in | ios::out | ios::ate);
temp.open("temp.txt",
ios::out | ios::app);
file.seekg(0);
file.read((char*)&a, sizeof(a));
// Till end of the file
while (!file.eof()) {
if (!strcmp(a.usernames(), uname)) {
int b;
cout << "\nEnter amount "
<< "to deposit:";
cin >> b;
a.balance = a.balance + b;
cout << "\nBalance is:"
<< a.balance;
temp.write((char*)&a, sizeof(a));
}
else {
temp.write((char*)&a, sizeof(a));
}
file.read((char*)&a, sizeof(a));
}
file.close();
temp.close();
remove("aaa.txt");
rename("temp.txt", "aaa.txt");
}
// Function to update user by
// depositing withdrawing money
void atm::updateuseraswithdraw(char* uname)
{
atm a;
fstream file, temp;
file.open("aaa.txt",
ios::in | ios::out | ios::ate);
temp.open("temp.txt",
ios::out | ios::app);
file.seekg(0);
file.read((char*)&a, sizeof(a));
// Till end of file is reached
while (!file.eof()) {
if (!strcmp(a.usernames(), uname)) {
int b;
cout << "\nEnter amount "
<< "to withdraw:";
cin >> b;
if (a.balance < b) {
cout
<< "\nInsufficient "
<< "balance to withdraw";
}
else {
a.balance = a.balance - b;
temp.write((char*)&a,
sizeof(a));
cout << "\nBalance is:"
<< a.balance;
}
}
else {
temp.write((char*)&a,
sizeof(a));
}
file.read((char*)&a, sizeof(a));
}
// Close the file
file.close();
temp.close();
remove("aaa.txt");
rename("temp.txt", "aaa.txt");
}
// Search user
int atm::searchspecificuser(
char* uname, int pass)
{
atm a;
fstream f;
// Open the file
f.open("aaa.txt", ios::in);
if (!f) {
cout << "Error in opening file..";
return 0;
}
// Read data from file
f.read((char*)&a, sizeof(a));
while (!f.eof()) {
if (!strcmp(a.usernames(), uname)) {
if (a.passwords() == pass) {
return 1;
}
}
f.read((char*)&a, sizeof(a));
}
// Close the file
f.close();
return 0;
}
// Search specific user
int atm::searchallusertodisplay(
char* uname)
{
atm a;
fstream file1;
// Open the file
file1.open("aaa.txt", ios::in);
if (!file1) {
cout << "Error in opening file..";
return 0;
}
// Read data from file
file1.read((char*)&a, sizeof(a));
while (!file1.eof()) {
if (!strcmp(a.usernames(), uname)) {
a.showData();
return 0;
}
file1.read((char*)&a, sizeof(a));
}
// Close the file
file1.close();
return 0;
}
// Driver Code
int main()
{
// Function Call
atmUser();
return 0;
} 输出：
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