- 1 year ago
Using a Windows DLL in Go with cgo
To use a Windows DLL in Go with cgo (cgo enables Go programs to call C code), you can follow these steps:
Create a C header file: First, create a C header file (.h) that defines the function signatures and any necessary types or constants for the DLL. Let's assume the DLL contains a function named
HelloWorld
that takes no arguments and returns a string:c// dll.h
#ifndef DLL_H
#define DLL_H
__declspec(dllexport) const char* HelloWorld();
#endif
Implement the C function: Implement the C function in a separate C source file (.c) that corresponds to the function signature defined in the header file. For example:
c// dll.c
#include "dll.h"
__declspec(dllexport) const char* HelloWorld() {
return "Hello, World!";
}
Build the DLL: Use a C compiler to build the DLL from the C source file(s) using the appropriate build commands for your development environment. For example, with GCC on Windows, you can use the following command:
vbnetgcc -shared -o mydll.dll dll.c
This will generate a DLL file named
mydll.dll
.Create a Go wrapper: In your Go code, create a wrapper to load and call the DLL function using cgo. For example:
go// main.go
package main
// #cgo CFLAGS: -g -Wall
// #cgo LDFLAGS: -L. -ldll
// #include "dll.h"
import "C"
import "fmt"
func main() {
result := C.GoString(C.HelloWorld())
fmt.Println(result)
}
In this example, the
#cgo
directives are used to specify the necessary C flags and linker flags. Update the directives with the appropriate filenames and library names based on your DLL.Build and run the Go program: Use the
go build
command to build the Go program. For example:gogo build -o myapp main.go
This will generate an executable file named
myapp
. Run the executable to see the output:bash./myapp
The output should be "Hello, World!" obtained from the DLL function call.
By following these steps, you can use a Windows DLL in Go using cgo. Ensure that the DLL is built correctly, and the necessary C header and source files are provided in your project. Update the filenames and function signatures in the example code to match your specific DLL.