C++流庫函數應用實例

C++ 流庫（iostream）是一個功能強大的輸入/輸出庫，它提供了格式化輸入/輸出功能，支持各種數據類型

1. 從鍵盤讀取整數和字符串：

#include<iostream>
#include<string>

int main() {
    int age;
    std::string name;

    std::cout << "Enter your name: ";
    std::cin >> name;

    std::cout << "Enter your age: ";
    std::cin >> age;

    std::cout << "Hello, "<< name << "! You are "<< age << " years old."<< std::endl;

    return 0;
}

2. 從文件讀取數據并計算平均值：

#include<iostream>
#include <fstream>
#include<vector>

int main() {
    std::ifstream input_file("data.txt");
    std::vector<double> numbers;
    double number;

    if (!input_file) {
        std::cerr << "Error opening file."<< std::endl;
        return 1;
    }

    while (input_file >> number) {
        numbers.push_back(number);
    }

    input_file.close();

    double sum = 0;
    for (const auto &num : numbers) {
        sum += num;
    }

    double average = sum / numbers.size();
    std::cout << "The average of the numbers in the file is: "<< average<< std::endl;

    return 0;
}

3. 將數據寫入文件：

#include<iostream>
#include <fstream>

int main() {
    std::ofstream output_file("output.txt");

    if (!output_file) {
        std::cerr << "Error opening file."<< std::endl;
        return 1;
    }

    std::string text = "Hello, World!";
    output_file<< text<< std::endl;

    output_file.close();

    std::cout << "Text has been written to the file."<< std::endl;

    return 0;
}

這些實例展示了 C++ 流庫的基本用法。你可以根據需要修改和擴展這些代碼以滿足你的需求。