What Is Cgo and How to Call C Code from Go

Cgo is a tool that allows Go code to call C functions and use C libraries by generating wrapper code during compilation. To call C code, define the C header includes and function declarations in a comment block immediately preceding import "C", then reference C symbols using the C. prefix in your Go code.

package main

/*
#include <stdio.h>
*/
import "C"

func main() {
	C.printf("Hello from C\n")
}

If linking against an external library, add #cgo LDFLAGS: -l<library_name> in the comment block before import "C".

Cgo is a bridge that lets your Go program talk to existing C code, like a translator between two different languages. You use it when you need to access fast, low-level C libraries that don't have a Go version yet. Think of it as a universal adapter that lets your modern Go app plug into older, high-performance C tools.