Question

目前已经编写了此简单的代码，试图弄清为什么每次都不计算特定单词。

#include "pch.h"
#include <fstream>
#include <string>
#include <iostream>

using namespace std;
int main()
{
    int t = 0;
    int a1 = 0;
    string a[100];
    ifstream food;

    food.open("food.txt");

    if (food.fail())
    {
        cout << "File can't open" << endl;

    }

    else
        cout << "File successfully opened" << endl;

    int i = 0;

    while (!food.eof())
    {
        // Tomato
        food >> a[i];
        if (a[i] == "tomato")
        {
            t = t + 1;
        }
        i++;

        // Apple
        food >> a[i];
        if (a[i] == "apple")
        {
            a1 = a1 + 1;
        }
        i++;
    }
    cout << "Amount of Tomatos: " << t << endl;
    cout << "Amount of Apples: " << a1 << endl;
}

我正在使用的文本文件：

apple
apple
tomato
apple
tomato
tomato

输出：

File successfully opened
Amount of Tomatoes: 2
Amount of Apples: 2

目的是查找列表中找到的每种食物的量。我目前只使用两种食物，但还会有更多。

Answer 1

您的代码有几个问题。

在循环中错误地使用eof()。首先执行读取操作之前，您无法检查eof()。
使用无边界检查的数组。因此，您根本不需要数组。
跳过单词，这就是为什么您没有计算期望值的原因。让我们以第一行apple为例。由于它不是"tomato"，因此可以跳过它并读取文件中的下一个单词"apple"，因此可以对它进行计数。但是您根本不算第一个apple。

您需要执行以下操作：

#include "pch.h"
#include <fstream>
#include <string>
#include <iostream>

using namespace std;

int main()
{
  int tomatoes = 0;
  int apples = 0;
  string s;
  ifstream food;

  food.open("food.txt");

  if (!food.is_open())
  {
    cout << "File can't open" << endl;
    return 0;
  }

  cout << "File successfully opened" << endl;

  while (food >> s)
  {
    // Tomato
    if (s == "tomato")
        ++tomatoes;

    // Apple
    else if (s == "apple")
        ++apples;
  }

  cout << "Amount of Tomatos: " << tomatoes << endl;
  cout << "Amount of Apples: " << apples << endl;

  return 0;
}

或者，如评论中提到的@ user463035818一样，您可以改用std::map：

#include "pch.h"
#include <fstream>
#include <string>
#include <iostream>
#include <map>

using namespace std;

int main()
{
  map<string, int> foods;
  string s;
  ifstream food;

  food.open("food.txt");

  if (!food.is_open())
  {
    cout << "File can't open" << endl;
    return 0;
  }

  cout << "File successfully opened" << endl;

  while (food >> s) {
    foods[s]++;
  }

  for (map<string, int>::iterator iter = foods.begin(); iter != foods.end(); ++iter) {
      cout << "Amount of " << iter->first << ": " << iter->second << endl;
  }

  /* or, if you are using C++11 or later...
  for (auto &item : foods) {
      cout << "Amount of " << item.first << ": " << item.second << endl;
  }
  */

  return 0;
}

计算在txt文件中找到单词的次数

1 个答案: