Home Backend Development C++ How Do I Import and Use Functions from DLLs in C ?

How Do I Import and Use Functions from DLLs in C ?

Dec 14, 2024 am 05:41 AM

How Do I Import and Use Functions from DLLs in C  ?

Importing Functions from DLLs: A Comprehensive Guide

Loading Dynamic Link Libraries (DLLs) allows your C programs to utilize functionality from external shared libraries. To access functions within a DLL, however, requires a different approach than importing functions from header files.

Loading the DLL with LoadLibrary

The LoadLibrary function loads a DLL into the current process's memory. This process does not automatically import the functions defined in the DLL.

Retrieving the Function Address with GetProcAddress

Once the DLL is loaded, you need to obtain the addresses of the functions you want to use. This is done using the GetProcAddress function.

#include <windows.h>

typedef int (__stdcall *f_funci)();  // Define function pointer type

int main() {
  HINSTANCE hGetProcIDDLL = LoadLibrary("...")

  // Retrieve function address
  f_funci funci = (f_funci)GetProcAddress(hGetProcIDDLL, "funci");
}
Copy after login

In the code snippet above, we define a function pointer type called f_funci that represents the function we want to import. The GetProcAddress function returns the address of the function within the DLL.

Exporting Functions from DLLs

To ensure the proper exporting of functions from a DLL, use the __declspec(dllexport) and __stdcall attributes.

int __declspec(dllexport) __stdcall funci() {
   // ...
}
Copy after login

The __declspec(dllexport) attribute indicates that the function should be exported from the DLL, and the __stdcall attribute specifies the calling convention used by the DLL.

Releasing the DLL Handle

After using the functions imported from the DLL, it's good practice to release the handle to the library. This is accomplished using the FreeLibrary function.

FreeLibrary(hGetProcIDDLL);
Copy after login

By following these steps, you can dynamically load DLLs and access their functions in C . This technique empowers you to extend the capabilities of your programs by utilizing reusable modules without the need for static linking or recompilation.

The above is the detailed content of How Do I Import and Use Functions from DLLs in C ?. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot Article Tags

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

What are the types of values ​​returned by c language functions? What determines the return value? What are the types of values ​​returned by c language functions? What determines the return value? Mar 03, 2025 pm 05:52 PM

What are the types of values ​​returned by c language functions? What determines the return value?

Gulc: C library built from scratch Gulc: C library built from scratch Mar 03, 2025 pm 05:46 PM

Gulc: C library built from scratch

C language function format letter case conversion steps C language function format letter case conversion steps Mar 03, 2025 pm 05:53 PM

C language function format letter case conversion steps

What are the definitions and calling rules of c language functions and what are the What are the definitions and calling rules of c language functions and what are the Mar 03, 2025 pm 05:53 PM

What are the definitions and calling rules of c language functions and what are the

distinct usage and phrase sharing distinct usage and phrase sharing Mar 03, 2025 pm 05:51 PM

distinct usage and phrase sharing

Where is the return value of the c language function stored in memory? Where is the return value of the c language function stored in memory? Mar 03, 2025 pm 05:51 PM

Where is the return value of the c language function stored in memory?

How does the C   Standard Template Library (STL) work? How does the C Standard Template Library (STL) work? Mar 12, 2025 pm 04:50 PM

How does the C Standard Template Library (STL) work?

How do I use algorithms from the STL (sort, find, transform, etc.) efficiently? How do I use algorithms from the STL (sort, find, transform, etc.) efficiently? Mar 12, 2025 pm 04:52 PM

How do I use algorithms from the STL (sort, find, transform, etc.) efficiently?

See all articles