How to return a C struct value from a go function

Question

I want to return a C struct value from a Go function. Assuming ProcessX() and ProcessY() are go methods which return integers (uint8 values):

package main

/*
struct Point {
    char x;
    char y;
};
*/

import "C"

//export CreatePoint
func CreatePoint(x uint8, y uint8) C.Point {
    xVal := ProcessX(x);
    yVal := ProcessY(y);
    return C.Point {x: xVal, y: yVal}
}

func main() {}

But this results in a build error: ".\main.go:13:36: could not determine kind of name for C.Point"

Edit:

Using go build -ldflags "-s -w" -buildmode=c-shared -o mylibc.dll .\main.go to compile in Windows 10 through mingw

Edit-2:

I have removed the empty line between the "C" import and the preceeding preamble, but couldn't avoid the error. The code is now like:

/*
struct Point {
    char x;
    char y;
};
*/
import "C"

rocka2q · Accepted Answer · 2022-05-10 13:01:22Z

1

I find reading the documentation useful to solve problems like this.

To access a struct type directly, prefix it with struct_, as in C.struct_stat.

cgo command

package main

/*
struct Point {
    char x;
    char y;
};
*/
import "C"

//export CreatePoint
func CreatePoint(x uint8, y uint8) C.struct_Point {
    xVal := ProcessX(x);
    yVal := ProcessY(y);
    return C.struct_Point {x: C.char(xVal), y: C.char(yVal)}
}

func ProcessX(x uint8) uint8 { return x | 'x'}
func ProcessY(y uint8) uint8 { return y | 'y'}

func main() {}

answered May 10, 2022 at 13:01

rocka2q

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