如何从文本文件中读取整数和字符串？

Question

I have a text file containing name, ability, attack, and defense on every line, for instance:

Bill Punch 10 5
Jack Jab 7 7
Joe Kick 8 4

I would like to read the file and store its content. I could use an array, but I want to be able to continue to add rows. So I've implemented a function to count the lines. Arrays like to complain about values not being static at runtime so I moved to trying a vector. Below is the code.

I'm attempting to insert every value into the x,y of the matrix, then go through and print it. But it's not working; it opens the command prompt and asks to input my file name. I do that, but then it just stops running.

Also, how can I return the vector to my main function?

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <string>
#include <vector>

using namespace std;

// Global Variables
int numLines = 0;
string fileName;
int countLines();
string openFile();

int main() {
    string name, attack;
    cout << "What is the name of your data file?" << endl;
    getline(cin, fileName);
    cout << countLines() << endl;
    cout << openFile() << endl;
}
int countLines() {
    ifstream dataFile(fileName);
    string line;
    while (getline(dataFile, line)) {
        numLines++;
    }
    return numLines;
}
string openFile() {
    vector<vector<int>> dataVec(numLines, vector<int>(4));
    ifstream dataFile(fileName);
    string line;
    while (getline(dataFile, line)) {
        for (int i = 0; i == numLines - 1; i++) {
            for (int o = 0; o == 4; o++) {
                cin >> dataVec[i][o];
            }
        }
    }
    while (getline(dataFile, line)) {
        for (int i = 0; i == numLines - 1; i++) {
            for (int o = 0; o == 4; o++) {
                cout << dataVec[i][o];
            }
        }
    }
    return dataVec;
}

Answer 1

There are better methods to read a CSV than you are using. Your method to read in a file of data are complicated and injecting defects. Simplifying your algorithm can reduce the number of defects.

For example, using a structure to model the data row. Let us call each line of data, a record.

struct Record
{
  std::string first_name;
  std::string last_name;
  int         number1;
  int         number2;
};

You can store the records into a simple std::vector :

std::vector<Record> database;

One method is to have the Record read in its data members:

    struct Record
    {
      std::string first_name;
      std::string last_name;
      int         number1;
      int         number2;
      friend istream& operator>>(istream& input, Record& r);
    };

istream& operator>>(istream& input, Record& r)
{
  input >> r.first_name;
  input >> r.last_name;
  input >> r.number1;
  input >> r.number2;
  return input;
};

This enables you to simplify your input loop:

Record r;
while (data_file >> r)
{
  database.push_back(r);
}

If you need to know the number of lines in the file, you could use database.size() . Otherwise, there is no need to know the number of lines in the file.

Similarly, you can write methods to print the record. If you overload operator<< , your print statement becomes:

cout << database[i] << endl;