How to Correctly Access a C Array of `const char*` Strings from Go?

Accessing C Array of const char * from Go

You're attempting to access a C array of const char from Go using cgo. Specifically, you have a C array of strings, and you want to index into it and convert the array entry into a Go string.

The Incorrect Approach

Your current code attempts to do so with pointer arithmetic:

myGoString := C.GoString((*C.char) (unsafe.Pointer(uintptr(unsafe.Pointer(C.myStringArray)) + uintptr(index) * unsafe.Sizeof(C.myStringArray))))

However, this approach is incorrect because it indexes along the characters of the string rather than up the array. As a result, you get the first few characters of each string instead of the entire string.

The Correct Solution

To correctly access the C array, it's safer and more convenient to first convert it into a Go slice:

import "unsafe"

const arraySize = 3

cStrings := (*[arraySize]*C.char)(unsafe.Pointer(&C.myStringArray))[:arraySize:arraySize]

for _, cString := range cStrings {
    fmt.Println(C.GoString(cString))
}

By converting the C array to a Go slice, you can then iterate over its elements and convert each element to a Go string using C.GoString().

Sample Output

This approach ensures that you get the entire string from the C array, as seen in the following sample output:

NAME_OF_FIRST_THING
NAME_OF_SECOND_THING
NAME_OF_THIRD_THING

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