How Can I Safely Access and Convert a C Array of `const char *` to Go Strings Using `cgo`?

Accessing C Arrays of Type const char * from Go Using Cgo

When working with C arrays of type const char * in Go, you may encounter difficulties in indexing and converting the entries into Go strings. This issue stems from the low-level pointer arithmetic involved in accessing the array elements.

To overcome this challenge, a safer and more convenient approach is to convert the C array into a Go slice. This intermediary step simplifies the conversion process while ensuring accuracy.

Converting a C Array to a Go Slice

arraySize := 3
cStrings := (*[1 << 30]*C.char)(unsafe.Pointer(&C.myStringArray))[:arraySize:arraySize]

This operation achieves the following:

• arraySize defines the number of elements in the array.
• *C.char declares a pointer to a C char type.
• unsafe.Pointer(&C.myStringArray) obtains the memory address of the first element in the myStringArray array.
• [:arraySize:arraySize] creates a Go slice pointing to the same C array elements, with a stride of arraySize.

Iterating Over the Slice and Converting Entries

Once the C array is converted into a slice, iterating over it becomes straightforward. Here's an example:

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

This loop prints each element of the C array after converting it into a Go string using C.GoString().

Sample Output

NAME_OF_FIRST_THING
NAME_OF_SECOND_THING
NAME_OF_THIRD_THING

By following this approach, you can effectively index and convert elements from a C array of type const char * into Go strings, avoiding the complexities of direct pointer arithmetic.

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