Golang and C Interaction: CGO

This is a creation in Article, where the information may have evolved or changed.

1. It is simple to refer to the C code in go, introduce the standard C code with a comment before the import "C", and then use the pseudo-package of c.xxx to refer to the identifier of the C code space. It is important to note that import "C" is a pseudo package and cannot be defined as import (...) with other package pieces.

2. Reference C code in go must manually release the C code object. The release method is C.free (unsafe. Pointer (XXX)), which also requires C code to include # include <stdlib.h>

3. The following must be understood in depth:

(1) Cgo recognizes this comment above import "C" statement.

(2) Any lines starting with #cgo followed by a space character is removed; These become directives for CGO.

(3) The remaining lines is used as a header when compiling the C parts of the package.

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Popular Memory:

(1) CGO is able to recognize comments for the import "C" statement.

(2) #cgo行用作cgo指令

(3) Other lines used as C header files

Point (2) is critical! Easily lead to duplicate definitions.

Practical questions:

Code Snippet 1:

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Package Main

/*

#include <stdlib.h>

#include "Prints.h"

*/

Import "C"

Import (

"FMT"

"Unsafe"

)

Func Main () {

Msg: = "This was a test for"

Cmsg: = c.cstring (msg)

Defer C.free (unsafe. Pointer (cmsg))

C.prints (CMSG)

Fmt. Println ("Done ...")

}

Introduce C code in the main package and use go run xxx.go to get an error. Go build--> to execute again, no error.

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The solution above is to define wrapper to encapsulate the C code. For example:

Package Myc

/*

#include <stdlib.h>

#include "Prints.h"

*/

Import "C"

Import "unsafe"

Func cprints (msg string) {

Cmsg: = c.cstring (msg)

Defer C.free (unsafe. Pointer (cmsg))

C.prints (CMSG)

}

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