C++词频统计程序开发与map应用详解

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

std::map<std::string, int> wordCount;

std::string normalize(const std::string& word) {
    std::string cleaned;
    for (char c : word) {
        if (std::isalpha(c)) {
            cleaned += std::tolower(c);
        }
    }
    return cleaned;
}

void processText(std::istream& in) {
    std::string line;
    while (std::getline(in, line)) {
        std::stringstream ss(line);
        std::string word;
        while (ss >> word) {
            std::string cleaned = normalize(word);
            if (!cleaned.empty()) {
                wordCount[cleaned]++;
            }
        }
    }
}

void printResults() {
    for (const auto& pair : wordCount) {
        std::cout << pair.first << ": " << pair.second << std::endl;
    }
}

int main() {
    std::ifstream file("input.txt");
    if (file.is_open()) {
        processText(file);
        file.close();
    } else {
        std::cout << "无法打开文件，使用标准输入：" << std::endl;
        processText(std::cin);
    }

    printResults();
    return 0;
}