C++ odr用法案例详解

// The main module. File: odr_test1.cpp 

#include <iostream>

void module1_print(); // declaration of an exeternal function

inline int f1()
{
	return 4;
}

class A
{
public:
	static double f()
	{
		return 4.1;
	}
};

const double C = 4.2;

constexpr double E = 4.5;

void print()
{
	std::cout << "main f1(): " << f1() << std::endl;
	std::cout << "main A::f(): " << A::f() << std::endl;
	std::cout << "main C: " << C << std::endl;
	std::cout << "main E: " << E << std::endl;
}

int main()
{
	module1_print();
	print();

	int i;
	std::cin >> i;
}
 

// File: module1.cpp

#include <iostream>

inline int f1()
{
	return 3;
}

class A
{
public:
	static double f()
	{
		return 3.1;
	}
};

const double C = 3.2;

constexpr double E = 3.5;

void module1_print()
{
	std::cout << "module1 f1(): " << f1() << std::endl;
	std::cout << "module1 A::f(): " << A::f() << std::endl;
	std::cout << "module1 C: " << C << std::endl;
	std::cout << "module1 E: " << E << std::endl;
}

1、在VS2017上运行的结果为：

2、使用clang进行编译

clang++ module1.cpp odr_test1.cpp

 运行结果：

若进行下面的编译：

clang++ odr_test1.cpp module1.cpp

 则结果如下 

3、使用gcc编译

g++ module1.cpp odr_test1.cpp -std=c++11

若进行如下编译

g++ odr_test1.cpp module1.cpp -std=c++11

二、如何解决这个问题

// The main module. File: odr_test2.cpp
#include <iostream>
void module2_print(); // declaration of an external function

namespace
{
inline int f1()
{
return 4;
}

class A
{
public:
static double f()
{
return 4.1;
}
};
}

const double C = 4.2;
constexpr double E = 4.5;

void print()
{
std::cout << "main f1(): " << f1() << std::endl;
std::cout << "main A::f(): " << A::f() << std::endl;
std::cout << "main C: " << C << std::endl;
std::cout << "main E: " << E << std::endl;
}

int main()
{
module2_print();
print();

int i;
std::cin >> i;
}

// File: module2.cpp

#include <iostream>

namespace
{
inline int f1()
{
return 3;
}

class A
{
public:
static double f()
{
return 3.1;
}
};
}

const double C = 3.2;
constexpr double E = 3.5;

void module2_print()
{
std::cout << "module2 f1(): " << f1() << std::endl;
std::cout << "module2 A::f(): " << A::f() << std::endl;
std::cout << "module2 C: " << C << std::endl;
std::cout << "module2 E: " << E << std::endl;
}

运行结果

到此这篇关于C++ odr用法案例详解的文章就介绍到这了,更多相关C++ odr用法内容请搜索我们以前的文章或继续浏览下面的相关文章希望大家以后多多支持我们！