C/C++ 跨文件共享全局变量

效果

项目

代码

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为了实现跨文件共享全局变量，我们可以使用 extern 关键字。extern 关键字用于声明一个变量，该变量在其他地方已经定义。它告诉编译器这个变量在其他文件中已经定义了，不需要重新分配内存空间，只需要引用即可。

效果

项目

代码

Common.h

#pragma once#include <iostream>using namespace std;struct para {bool  state;int   num;string name;
};//声明全局变量
extern  para  g_static_para;

Common.cpp

#pragma once
#include "Common.h"//定义全局变量
para  g_static_para;

init_class.h

#pragma once#include <iostream>
#include "Common.h"using namespace std;class init_class
{public:void init();};

init_class.cpp

#include "init_class.h"
#include "Common.h"void init_class::init()
{cout << "参数初始化 全局变量 g_static_para" << endl;g_static_para.state = true;g_static_para.num = 20;g_static_para.name = "测试信息2";
}

use_class.h

#pragma once#include <iostream>
#include "Common.h"using namespace std;class use_class
{public:void print();};

use_class.cpp

#include "use_class.h"void use_class::print() {cout << "打印参数 全局变量 g_static_para" << endl;cout << "g_static_para.state:" << g_static_para.state << endl;cout << "g_static_para.num:" << g_static_para.num << endl;cout << "g_static_para.name:" << g_static_para.name << endl;
}

ConsoleApplication1-test.cpp

#pragma once
#include <iostream>
#include "Common.h"
#include "init_class.h"
#include "use_class.h"using namespace std;int main()
{std::cout << "Hello World!\n";init_class ic;use_class uc;std::cout << "----------------------\n";g_static_para.state = false;g_static_para.num = 10;g_static_para.name = "测试信息1";uc.print();std::cout << "----------------------\n";ic.init();std::cout << "----------------------\n";uc.print();
}