好的，所以我正在尝试编写一个程序，将密码和用户名存储在一个文件中（我还没有写他们写入文件的部分，稍后会写），但是我的代码部分读取文件导致它无法工作（无输出），即使它在 VS 代码中编译没有错误。老实说，我也不完全理解我写的东西（我只是看了一个 youtube 视频），所以我一定是遗漏了一些关于代码的东西。 有关额外信息，我使用 C++ 20 和 clang++ 作为我的编译器。 我已经在下面发布了我的代码以供参考。
#include <iostream>
#include <cstdio>
#include <vector>
#include <fstream>
using namespace::std;
class user {
private:
string username;
string password;
public:
user(string user, string pass) {
username = user;
password = pass;
}
void SetUsername(string user) {
username = user;
}
void SetPassword(string pass) {
password = pass;
}
void ChangeUsername(string user) {
username = user;
}
void ChangePassword(string pass) {
password = pass;
}
string GetUsername() {
return username;
}
string GetPassword() {
return password;
}
};
int main() {
string listUsernames[1000];
string listPasswords[1000];
vector <user>list;
string username;
string password;
string prompt;
bool loginSuccess = false;
bool success = false;
int counter = 0;
int lines = 0;
/*
This part is like messsing it up
Starting from here:
*/
ifstream file;
file.open("usernames.txt");
while(!file.eof()) {
getline(file, listUsernames[lines]);
lines++;
}
file.close();
lines = 0;
file.open("passwords.txt");
while(!file.eof()) {
getline(file, listPasswords[lines]);
lines++;
}
file.close();
for(int i = 0; i < lines; i++) {
user oldUser(listUsernames[i], listPasswords[i]);
list.push_back(oldUser);
}
/*
Ending here
*/
cout << "\tWelcome user! Please choose to login or create an account below.\n";
do{
cout << "\tType \"Login\" to login or \"Create\" to create a new account\n";
cin >> prompt;
if(prompt == "Login") {
do{
cout << "Username: ";
cin >> username;
cout << "Password: ";
cin >> password;
for(int i = 0; i < list.size(); i++) {
if(username == list[i].GetUsername() && password == list[i].GetPassword()) {
cout << "Hello " << list[i].GetUsername() << "!\n\n";
loginSuccess = true;
success = true;
}
}
if(!loginSuccess) {
cout << "Incorrect username or password";
counter++;
if(counter < 2) {
cout << ", please try again.\n";
}
else {
cout << "\nMaybe you should try creating an account! \n";
}
}
} while(!loginSuccess && counter < 2);
}
else if(prompt == "Create") {
string newUsername;
string newPassword;
cout << "What would you like your username to be? Please enter: ";
cin >> newUsername;
cout << "What would you like your password to be? Please enter: ";
cin >> newPassword;
user newUser(newUsername, newPassword);
list.push_back(newUser);
cout << "Success!\n";
ofstream myfile;
myfile.open("usernames");
myfile << newUsername;
myfile.close();
myfile.open("passwords");
myfile << newPassword;
myfile.close();
}
else {
cout << "Sorry, that input was not understood\n";
cout << "Please try again\n";
}
} while(!success);
return 0;
}
你的错误：
while (!file.eof())修复后：
ifstream file;
file.open("usernames");
while(getline(file, listUsernames[lines])) {
lines++;
}
file.close();
lines = 0;
file.open("passwords");
while(getline(file, listPasswords[lines])) {
lines++;
}
file.close();
#include <iostream>
#include <cstdio>
#include <vector>
#include <fstream>
#include <cassert>
struct User
{
std::string username;
std::string password;
};
std::vector<std::string> from_file(const std::string& file_name)
{
auto content = std::vector<std::string>{};
auto line = std::string{};
auto file = std::ifstream{file_name};
while(getline(file, line)) {
content.emplace_back(std::move(line));
}
return content;
}
bool login( const std::vector<User>& users )
{
constexpr auto max_retry = 2;
auto counter = 0U;
while(counter < max_retry)
{
auto username = std::string{};
auto password = std::string{};
std::cout << "Username: ";
std::cin >> username;
std::cout << "Password: ";
std::cin >> password;
for(const auto& user : users) {
if(user.username == username && user.password == password) {
std::cout << "Hello " << username << "!\n\n";
return true;
}
}
std::cout << "Incorrect username or password";
++counter;
if(counter < max_retry) {
std::cout << ", please try again.\n";
}
else {
std::cout << "\nMaybe you should try creating an account! \n";
}
}
return false;
}
constexpr auto usernames_file = "usernames.txt";
constexpr auto passwords_file = "passwords.txt";
bool create(std::vector<User>& users)
{
auto username = std::string{};
auto password = std::string{};
std::cout << "What would you like your username to be? Please enter: ";
std::cin >> username;
std::cout << "What would you like your password to be? Please enter: ";
std::cin >> password;
users.emplace_back(User{username, password});
std::cout << "Success!\n";
{
auto file = std::ofstream{usernames_file};
file << username;
}
{
auto file = std::ofstream{passwords_file};
file << password;
}
return true;
}
int main()
{
auto list_usernames = from_file(usernames_file);
auto list_passwords = from_file(passwords_file);
assert(list_usernames.size() == list_passwords.size());
auto users = std::vector<User>{};
for(auto i = 0; i < list_usernames.size(); ++i)
{
users.emplace_back(User{list_usernames[i], list_passwords[i]});
}
std::cout << "\tWelcome user! Please choose to login or create an account below.\n";
auto success = false;
while(!success)
{
std::string prompt;
std::cout << "\tType \"Login\" to login or \"Create\" to create a new account\n";
std::cin >> prompt;
if(prompt == "Login")
{
success = login(users);
}
else if(prompt == "Create")
{
success = create(users);
}
else
{
std::cout << "Sorry, that input was not understood\n";
std::cout << "Please try again\n";
}
}
return 0;
}