C++进阶（1）——前景提要

前言

由于最近的项目需要用到C++，感觉之前大学没有好好学习，以及C++不断更新的新特性，需要整理一份新的手册，这个栏目的内容将主要涉及到C++11~C++23的核心特性。 首先我们从复习开始：

前置基础复习

1. 基础语法：变量、分支循环、数组、函数、指针、引用
2. 面向对象基础：类、封装、构造 / 析构、继承、多态、访问控制
3. 内存基础：栈 / 堆、new/delete、静态变量、作用域
4. 基础 STL：vector、string、map、循环迭代器

我们将会使用一套代码学习体验到以上所有特性，首先给出代码结构

Person.h

#pragma once
#ifndef BASE_GRAMMER_H
#define BASE_GRAMMER_H

#include <iostream>
#include <vector>
#include <string>
#include <map>

// 全局工具函数 仅声明
int add(int a, int b);
void changeByPtr(int* p);
void changeByRef(int& r);

// 父类 BasePerson
class BasePerson {
private:
	std::string name;
	int age;
	static int totalCnt;
protected:
	std::string id;
public:
	BasePerson(std::string n = "未知", int a = 0);
	virtual ~BasePerson();

	void setName(std::string n);
	std::string getName() const;
	void setAge(int a);
	int getAge() const;

	virtual void showInfo();
	static int getTotalCnt();
};

// 子类 Student 声明
class Student : public BasePerson
{
private:
	int score;
public:
	Student(std::string n, int a, int s, std::string i);
	void showInfo() override;
	virtual ~Student();
	void setScore(int s);
};

#endif

Person.cpp

#include "Person.h"

// 静态变量唯一初始化位置
int BasePerson::totalCnt = 0;

int add(int a, int b)
{
    return a + b;
}

void changeByPtr(int* p)
{
    *p = 999;
}

void changeByRef(int& r)
{
    r = 666;
}

// BasePerson 构造
BasePerson::BasePerson(std::string n, int a) : name(n), age(a)
{
    totalCnt++;
    std::cout << "【Base构造】创建人物：" << name << std::endl;
}

// 虚析构
BasePerson::~BasePerson()
{
    totalCnt--;
    std::cout << "【Base析构】销毁人物:" << name << std::endl;
}

void BasePerson::setName(std::string n) { name = n; }
std::string BasePerson::getName() const { return name; }
void BasePerson::setAge(int a) { age = a; }
int BasePerson::getAge() const { return age; }

void BasePerson::showInfo()
{
    std::cout << "父类人物 | 姓名:" << name << " 年龄:" << age << std::endl;
}

int BasePerson::getTotalCnt()
{
    return totalCnt;
}

// Student 子类实现
Student::Student(std::string n, int a, int s, std::string i)
    : BasePerson(n, a), score(s)
{
    id = i;
    std::cout << "【Student构造】学生入学" << std::endl;
}

void Student::showInfo()
{
    std::cout << "子类学生 | 姓名:" << getName()
        << " 学号：" << id
        << " 分数:" << score << std::endl;
}

Student::~Student()
{
    score = 0;
    std::cout << "【Student析构】学生毕业" << std::endl;
}

void Student::setScore(int s)
{
    score = s;
}

main.cpp

#include "Person.h"
#include <vector>
#include <map>

#ifdef _WIN32
#include <windows.h>
#endif

int main() {
#ifdef _WIN32
    SetConsoleOutputCP(CP_UTF8);  // Windows 控制台使用 UTF-8 显示中文
#endif

    std::cout << "========== 1. 基础语法：变量、分支、循环、数组、指针、引用 ==========\n";
    int num1 = 10, num2 = 20;
    double pi = 3.14;
    bool flag = true;

    if (num1 > num2)
    {
        std::cout << "num1更大\n";
    }
    else
    {
        std::cout << "num2更大\n";
    }

    int arr[5] = { 1, 2, 3, 4, 5 };
    std::cout << "数组遍历：";
    for (int i = 0; i < 5; i++)
    {
        std::cout << arr[i] << " ";
    }
    std::cout << std::endl;

    std::cout << "add(10,20) = " << add(num1, num2) << std::endl;

    int x = 100;
    int* p_x = &x;
    changeByPtr(p_x);
    std::cout << "指针修改后x = " << x << std::endl;

    int y = 200;
    int& ref_y = y;
    changeByRef(ref_y);
    std::cout << "引用修改后y = " << y << "\n\n";

    std::cout << "========== 2. 内存管理：栈、堆、new/delete、静态变量 ==========\n";
    int* heapNum = new int(888);
    std::cout << "堆内存数值：" << *heapNum << std::endl;

    int* heapArr = new int[3] {10, 20, 30};
    std::cout << "堆数组：" << heapArr[0] << " " << heapArr[1] << " " << heapArr[2] << std::endl;
    delete heapNum;
    delete[] heapArr;

    std::cout << "当前人物总数(初始)：" << BasePerson::getTotalCnt() << "\n\n";

    std::cout << "========== 3. 面向对象：封装、构造析构、继承、多态、访问控制 ==========\n";
    BasePerson p("张三", 30);
    std::cout << "通过set修改姓名：";
    p.setName("张三三");
    std::cout << p.getName() << std::endl;
    std::cout << "当前人物总数：" << BasePerson::getTotalCnt() << std::endl;

    Student stu("李四", 18, 95, "2026001");
    std::cout << "当前人物总数：" << BasePerson::getTotalCnt() << std::endl;

    BasePerson* polyObj = new Student("王五", 17, 98, "2026002");
    std::cout << "\n多态调用showInfo：";
    polyObj->showInfo();
    delete polyObj;
    std::cout << "释放多态对象后总数：" << BasePerson::getTotalCnt() << "\n\n";

    std::cout << "========== 4. STL：vector、string、map、迭代器 ==========\n";
    std::string str = "Hello C++ STL";
    std::cout << "string长度：" << str.size() << std::endl;
    str += " !";
    std::cout << "拼接后字符串：" << str << std::endl;

    std::vector<int> vec;
    vec.push_back(100);
    vec.push_back(200);
    vec.push_back(300);
    std::cout << "\nvector迭代器遍历：";
    std::vector<int>::iterator it = vec.begin();
    for (; it != vec.end(); ++it)
    {
        std::cout << *it << " ";
    }
    std::cout << std::endl;

    std::cout << "范围for遍历vector：";
    for (auto val : vec)
    {
        std::cout << val << " ";
    }
    std::cout << std::endl;

    std::map<std::string, int> scoreMap;
    scoreMap["语文"] = 90;
    scoreMap["数学"] = 99;
    scoreMap["英语"] = 85;

    std::cout << "\nmap迭代器遍历：" << std::endl;
    std::map<std::string, int>::iterator mapIt = scoreMap.begin();
    for (; mapIt != scoreMap.end(); ++mapIt)
    {
        std::cout << mapIt->first << " : " << mapIt->second << std::endl;
    }

    std::cout << "\n========== 程序结束，局部对象自动析构 ==========\n";
    return 0;
}

根目录CMakeLists.txt

# 收集当前模块全部源码
set(STAGE1_SRC
    "Person.h"
    "Persion.cpp"
    "main.cpp"
    
)

# 整个子模块用 C++23
set(CMAKE_CXX_STANDARD 23 PARENT_SCOPE) # 仅当前目录生效，不污染父目录
set(CMAKE_CXX_STANDARD_REQUIRED ON PARENT_SCOPE)

# 直接生成独立可执行程序
add_executable(stage1_base_demo ${STAGE1_SRC})

# 暴露当前模块头文件路径，内部#include无相对路径
target_include_directories(stage1_base_demo PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})

# VS解决方案资源管理器文件分组美化
source_group("stage1_base 基础语法模块源码" FILES ${STAGE1_SRC})

二级路由CMakeLists.txt

# stage二级目录总控CMake
# 根据开关选择性加载三级子模块
if(BUILD_STAGE1_BASE)
    add_subdirectory(stage1_base)
endif()

# 后续新增模块在这里追加：
# option(BUILD_STAGE2_OOP "面向对象模块" ON)
# if(BUILD_STAGE2_OOP)
#     add_subdirectory(stage2_oop)
# endif()

子模块CMakeLists.txt

# 收集当前模块全部源码
set(STAGE1_SRC
    "Person.h"
    "Persion.cpp"
    "main.cpp"
    
)

# 整个子模块用 C++23
set(CMAKE_CXX_STANDARD 23 PARENT_SCOPE) # 仅当前目录生效，不污染父目录
set(CMAKE_CXX_STANDARD_REQUIRED ON PARENT_SCOPE)

# 直接生成独立可执行程序
add_executable(stage1_base_demo ${STAGE1_SRC})

# 暴露当前模块头文件路径，内部#include无相对路径
target_include_directories(stage1_base_demo PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})

# VS解决方案资源管理器文件分组美化
source_group("stage1_base 基础语法模块源码" FILES ${STAGE1_SRC})