Count number of times a word is found in txt file - c++

Question

Currently have this simple code written, trying to figure out why it's not counting specific words every time.
#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;
}
The text file I'm using:
apple
apple
tomato
apple
tomato
tomato
The output:
File successfully opened
Amount of Tomatoes: 2
Amount of Apples: 2
The purpose is to find the amount of each food found in the list. I'm currently only using two kinds of food but will have many more.

Answer 1

There are several problems with your code.
using eof() in a loop incorrectly. You can't check eof() before performing a read operation first.
using an array without bounds checking. For that matter, you don't need an array at all.
skipping words, which is why you are not counting everything you are expecting. Let's take the very first line, apple. Since it is not a "tomato", you skip it and read the next word in the file, which is "apple", so you count it. But you didn't count the 1st apple at all.
You need to do something more like this instead:
#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;
}
Alternatively, as #user463035818 mentioned in comments, you can use a std::map instead:
#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;
}