如何从文件中读取单词，将它们分配给数组并分析其内容？

Question

I (a student whose professor encourages online research to complete projects) have an assignment where I have to analyze the contents of a file (frequency of certain words, total word cout, largest and smallest word) and I'm getting stuck on even opening the file so the program can get words out. I've tried to just count the words that it reads and i get nothing. As I understand it, the program should be opening the selected .txt file, going through its contents word by word and outputing it right now.

Here's code:

#include <iostream>
#include <string>
#include <cctype>
#include <fstream>
#include <sstream>

    string selected[100];
    //open selected file.
    ifstream file;
    file.open(story.c_str());
    string line;
    if (!file.good())
    {
        cout << "Problem with file!" << endl;
        return 1;
    }
    while (!file.eof())
    {
        getline(file, line);

        if (line.empty())
            continue;

        istringstream iss(line);

        for (string word; iss >> word;)
            cout << word << endl;

    ```

Answer 1

Because of the simplicity of the attached code, I will not give detailed explanations here. With the usage of std::algorithm every task can be performed in a one-liner.

We will read the complete source file into one std::string . Then, we define a std::vector and fill it with all words. The words are defined by an ultra simple regex.

The frequency is counted with a standard approach using std::map .

#include <fstream>
#include <string>
#include <iterator>
#include <vector>
#include <regex>
#include <iostream>
#include <algorithm>
#include <map>

// A word is something consiting of 1 or more letters
std::regex patternForWord{R"((\w+))"};

int main() {

    // Open file and check, if it could be opened
    if (std::ifstream sampleFile{ "r:\\sample.txt" }; sampleFile) {

        // Read the complete File into a std::string
        std::string wholeFile(std::istreambuf_iterator<char>(sampleFile), {});

        // Put all words from the whole file into a vector
        std::vector<std::string> words(std::sregex_token_iterator(wholeFile.begin(), wholeFile.end(), patternForWord, 1), {});

        // Get the longest and shortest word
        const auto [min, max] = std::minmax_element(words.begin(), words.end(),
            [](const std::string & s1, const std::string & s2) { return s1.size() < s2.size(); });

        // Count the frequency of words
        std::map<std::string, size_t> wordFrequency{};
        for (const std::string& word : words) wordFrequency[word]++;

        // Show the result to the user
        std::cout << "\nNumber of words: " <<  words.size() 
            << "\nLongest word: " << *max << "  (" << max->size() << ")"
            << "\nShortest word: " << *min << "  (" << min->size() << ")"
            << "\nWord frequencies:\n";
        for (const auto& [word, count] : wordFrequency) std::cout << word << " --> " << count << "\n";

    }
    else {
        std::cerr << "*** Error:  Problem with input file\n\n";
    }
    return 0;
}