Call C Functions in Go and Vice Versa

Types

String:

hostname := C.CString("100.100.24.81")
defer C.free(unsafe.Pointer(hostname))
 

Int

port := C.int(102)
 

Struct

struct Greetee {
    const char *name;
    int year;
};
 
g := C.struct_Greetee{
    name: name,
    year: year,
}
 

Print Hello World

In this example we want to print something with the help of C function.

  1. we need to import "C".
  2. we can write C code right above import "C" line. you must comment them out. it doesn't matter that they are commented out they will work fine.
  3. import the C libraries that we need. Here we need // #include <stdio.h> and // #include <stdlib.h> 4- now, all the function of the imported libraries, has added to "C" namespace. see the example to find out how it works.
package main

// #include <stdio.h>
// #include <stdlib.h>
import "C"
import "unsafe"

func main() {
	cs := C.CString("This is a \"Hello World\" message from C.\n")
	defer func() {
		C.free(unsafe.Pointer(cs))
	}()
	C.puts(cs)
}
 

Run it :

$ go env -w CGO_ENABLED=1
$ go build -o ./bin/hello ./main.go

$ ./bin/hello
 

Note

To build the program you have to have GCC or G++ on your machine. Linux, Windows Don't forget to check add to path while installing

Result:

This is a "Hello World" message from C.