Examples of calling C code from Golang

c2.c

#include<stdio.h>

void inCFile() {
    printf("I am in C code in a .c file now!\n");
}

c2.go

package main

/*
extern void inCFile();
*/
import "C"
import "fmt"

func main() {
    fmt.Println("I am in Go code now!")
    C.inCFile()
}

c3.c

#include<stdio.h>
#include "_cgo_export.h"

void inCFile() {
    printf("I am in C code in a .c file now!\n");
    callFromC();
}

c3.go

package main

/*
#include<stdio.h>
extern void inCFile();
*/
import "C"
import "fmt"

func main() {
    fmt.Println("I am in Go code now!")
    C.inCFile()
}

//export callFromC
func callFromC() {
    fmt.Println("I am in Go code but I was called from C!")
}

cgo1.go

package main

//#include<stdio.h>
//void inC() {
//    printf("I am in C code now!\n");
//}
import "C"
import "fmt"

func main() {
    fmt.Println("I am in Go code now!")
    C.inC()
}