在C ++中包含C代码 [英] Including C Code in C++

问题描述

我试图将C代码包含到一个简单的C ++程序，但我遇到了一个意想不到的问题 - 当我尝试编译程序g ++给出以下错误：

  /tmp/cccYLHsB.o：在函数main中：
 test1.cpp :(。text + 0x11）：未定义的引用
  

我搜索了一个解决方案，发现本教程：

a href =http://www.parashift.com/c++-faq/overview-mixing-langs.html> http://www.parashift.com/c++-faq/overview-mixing-langs.html a>

似乎对我的程序没有区别，所以我有点失落...

我的C ++程序如下所示：

test1.ccp

  #include< iostream> 
 using namespace std; 
 
 externC{
 #includesample1.h
} 
 
 int main（void）
 {
 int x = add（3）; 
 
 cout<< x的当前值是< x < endl; 
 
 return 0; 
} 
  

sample1标题和函数如下所示：

sample1.h

  #include< stdio.h> 
 
 double add（const double a）; 
  

sample1.c

  #includesample1.h
 
 double add（const double a）
 {
 printf（Hello World\\\
）; 
 
 return a + a; 
} 
  

对于编译，我首先使用g ++和sample1.o编译test1.o gcc（尝试g ++也没有差别）

  g ++ -c test1.cpp 
 
 gcc  - c sample1.c 
  

这样工作正常。然后我尝试这样链接程序：

  g ++ sample1.o test1.o -o test 
  
 
 
 
这是我收到上述错误的地方
  test1.cpp :(。text + 0x11）：未定义引用`add'
  
 
 
 < 
 
 
 
任何帮助都非常感谢！
 
 
 
尊敬
 
 
 
 jules 
解决方案
工作正如预期。请确保您没有不小心使用 g ++ 编译了 sample1.c 。
 
I'm trying to include C code into a simple C++ program but I ran into an unexpected problem - when I try to compile the program g++ gives the following error:
/tmp/cccYLHsB.o: In function `main':
test1.cpp:(.text+0x11): undefined reference to `add'
I searched for a solution and found this tutorial:

http://www.parashift.com/c++-faq/overview-mixing-langs.html

There seems to be no difference to my program so I'm a bit lost... 

My C++ program looks like this:

test1.ccp
#include <iostream>
using namespace std;

extern "C" {
#include "sample1.h"
}

int main(void)
{
    int x= add(3);

    cout << "the current value of x is " << x << endl;

    return 0;
}
The sample1 header and function look like this:

sample1.h
#include <stdio.h>

double add(const double a);
sample1.c
#include "sample1.h"

double add(const double a)
{
    printf("Hello World\n");

        return a + a;
}
For compilation I first compile a test1.o with g++ and sample1.o with gcc (tried g++ also but makes no difference)
g++ -c test1.cpp

gcc -c sample1.c
That works as expected. Afterwards I try to link the program like this:
g++ sample1.o test1.o -o test
This is where I get the error mentioned above
test1.cpp:(.text+0x11): undefined reference to `add' 
I have the feeling that I'm missing something important but just can't see it.

Any help is highly appreciated!

Regards

jules
解决方案
It works just as expected. Make sure you haven't accidentally compiled sample1.c with g++.

                        
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