[英]C++ dll in C program
I'd like to create a dll library from C++ code and use it in C program. 我想用C ++代码创建一个dll库,并在C程序中使用它。 I'd like to export only one function:
我只想导出一个函数:
GLboolean load_obj (const char *filename, GLuint &object_list);
Header file from library: 来自库的头文件:
#ifndef __OBJ__H__
#define __OBJ__H__
#include <windows.h>
#include <GL/gl.h>
#include <GL/glext.h>
#include <GL/glu.h>
#include <GL/glut.h>
#if defined DLL_EXPORT
#define DECLDIR __declspec(dllexport)
#else
#define DECLDIR __declspec(dllimport)
#endif
extern "C" GLboolean load_obj (const char *filename, GLuint &object_list);
#endif // __3DS__H__
in .cpp (in library project) function is also declared as: 在.cpp(在库项目中)函数也声明为:
extern "C" GLboolean load_obj (const char *filename, GLuint &object_list)
{
code...
}
File .lib is added in VS project options (Linker/Input/Additional dependencies). 文件.lib添加在VS项目选项(链接器/输入/附加依赖项)中。 .dll is in folder where .exe is.
.dll位于.exe所在的文件夹中。 When I compile C project - error:
当我编译C项目时 - 错误:
Error 1 error C2059: syntax error : 'string'
It is about part "extern "C" " in header file. 它是关于头文件中的“extern”C“”部分。
I've tried to change header file to: 我试图将头文件更改为:
extern GLboolean load_obj (const char *filename, GLuint &object_list);
then 然后
Error 1 error C2143: syntax error : missing ')' before '&'
Error 2 error C2143: syntax error : missing '{' before '&'
Error 3 error C2059: syntax error : '&'
Error 4 error C2059: syntax error : ')'
and even when I changed & to * appeared: 甚至当我改变&为*出现了:
Error 6 error LNK2019: unresolved external symbol _load_obj referenced in function _main main.obj
I've no idea why it is wrong. 我不知道为什么这是错的。 .lib .h and .dll are properly added.
.lib .h和.dll已正确添加。
The parameter " GLuint &object_list
" means "pass a reference to an GLuint here". 参数“
GLuint &object_list
”表示“在此处传递对GLuint的引用”。 C doesn't have references. C没有参考。 Use a pointer instead.
请改用指针。
// declaration
extern "C" GLboolean load_obj (const char *filename, GLuint *object_list);
// definition
GLboolean load_obj (const char *filename, GLuint *object_list)
{
code...
}
C has no references, as David pointed out. 大卫指出,C没有参考。
In addition, take out extern "C". 另外,取出extern“C”。 C does not have a use for nor know about it.
C没有用途也不了解它。
If you need to share the header, do something like: 如果您需要共享标题,请执行以下操作:
#ifdef __cplusplus
extern "C" {
#endif
/* extern "C" stuff */
#ifdef __cplusplus
}
#endif
In C, __cplusplus won't be defined. 在C中,不会定义__cplusplus。
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