runoob_03_iostream

/*
 * @Author: by777
 * @Date: 2025-03-20 20:18:41
 * @LastEditors: by777
 * @LastEditTime: 2025-03-20 20:33:19
 * @FilePath: /cxx_stl/runoob_03.cpp
 * @Description: https://www.runoob.com/cplusplus/cpp-libs-iostream.html
 * 
 * Copyright (c) 2025 by by777, All Rights Reserved. 
 */
#include <iostream>
// 对输出格式化，例如设置宽度精度和对齐方式
#include <iomanip>
int main(int argc, const char** argv) {
    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;

    std::cerr<<"Error: this is an error message"<<std::endl;
    std::clog<<"Log: this is a log message"<<std::endl;


    double pi = 3.14159;
    // 设置输出精度
    std::cout<<std::setprecision(3)<<pi<<std::endl;

    // 设置宽度和对齐方式
    std::cout<<std::setw(20)<<std::left<<pi<<std::endl;
    std::cout<<std::setw(20)<<std::right<<pi<<std::endl;

    // 检查流的状态
    std::cout<<"Enter your name: ";
    std::cin>>name;
    if(std::cin.fail()){

        std::cerr<<"Invalid input!"<<std::endl;
    }else{
        std::cout<<"You entered: "<<name<<std::endl;
    }

    // 处理字符串输入: getline可以读取包含空格的整行输入
    std::string fullName;
    std::cout << "Enter your full name: ";
    std::getline(std::cin, fullName);
    std::cout << "Hello， " <<fullName<< "!"<<std::endl;



    return 0;
}