c/c++混编

/* head.h */
#ifndef __SUM_H__
#define __SUM_H__

#ifdef __cplusplus
extern "C" {
#endif
    int add(int a, int b);
    int sub(int a, int b);

#ifdef __cplusplus
}
#endif

#endif /* __SUM_H__ */

sum.cpp

#include <iostream>

#include "head.h"

using namespace std;

int main()
{
    int a, b;
    cout << "请输入两个数字：" ;
    
    cin >> a >> b;

    cout << "相加：" << add(a, b) << endl;
    cout << "相减：" << sub(a, b) << endl;
}

test.c

#include <stdio.h>
#include "head.h"

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

 编译测试：g++ sum.cpp test.c

或者将c文件编译成.o文件:gcc -c test.c 生成test.o 然后: g++ sum.cpp test.o