从 .txt 文件读取并输入到 parrel 数组 C++

Question

这是文本文件。

4

MB-1111-1111 1111 222.22

MB-2222-2222 2222 333.33

B1-3333-3333 3333 444.44

4444 4444 555.55

顶部的 4 是帐户总数。 以下每一行按以下顺序排列：账户名称/PIN/余额。

我如何读取这个 .txt 文件并将这些值中的每一个放入一个数组中？

这是我到目前为止所拥有的，但我完全迷失了。

#include <iostream>
using namespace std;

int readAccts() {
    ifstream f;
    int accounts_total, max=99999.99, pin, balance;
    char account_name;
    f.open("accounts.txt");
    if (!f.fail()) {
        f >> accounts_total;
        f >> account_name;

        f.close();
        return account_name;
    }
    else {
        cout << "Error reading accounts!" << endl;
        accounts_total = -1;
        f.close();
        return accounts_total;
        
    }
    return accounts_total;
}

Answer 1

我会在这里提出一些建议。

• 不要使用并行数组 => 最好使用类或结构
• 将对象存储在列表中
• 您根本不需要存储条目数

假设这是filename.txt

MB-1111-1111 1111 222.22

MB-2222-2222 2222 333.33

B1-3333-3333 3333 444.44

4444 4444 555.55

// create a struct to hold the data
struct Account {
    std::string Name;
    std::string Pin;
    double Balance;
}

// open the file
std::ifstream input( "filename.txt" );
// create a list for all accounts
std::list<Account> Accounts;
// iterate over each line
for( std::string line; getline( input, line ))
{
    // maybe not neccessary but I'm not sure because of the belance and the casting
    std::string name, pin, balance;
    std::stringstream linestream(line);
    // get the line values
    if(linestream >> name >> pin >> balance) {
        Account account;
        // set values for object
        account.Name = name;
        account.Pin = pin;
        // string to double
        account.Balance = std::stod(balance);
        // store account in list
        Accounts.push_back(account);
    }
}

---

当你真的需要数组时：

4

MB-1111-1111 1111 222.22

MB-2222-2222 2222 333.33

B1-3333-3333 3333 444.44

4444 4444 555.55

// open the file
std::ifstream input( "filename.txt" );
std::string firstLine;
getline( input, firstLine );
// get the number of following lines
int lines = std::stoi(firstLine);
// create arrays with the capacity of lines
std::string* Names = new std::string[lines];
std::string* Pins = new std::string[lines];
double* Balances = new double[lines];

// iterate over each line
int ctr = 0;
for( std::string line; getline( input, line ))
{
    std::string name, pin, balance;
    std::stringstream linestream(line);
    // get the line values
    if(linestream >> name >> pin >> balance) {
        // store values in corresponding arrays
        Names[ctr] = name;
        Pins[ctr] = pin;
        Balances[ctr] = std::stod(balance);
        // increment counter for next array position
        ctr++;
    }
}
// do something cool with the values
// ...

// free memory after you'r done
delete[] Names;
delete[] Pins;
delete[] Balances;