How to pass a wide string to a C library function that accepts wchar_t** as an argument?

Table of Contants

Introduction

When interfacing with C libraries in Python using the ctypes module, you may encounter functions that accept wchar_t** as an argument. This type represents a pointer to a pointer of wide characters, which is commonly used for wide strings. In this guide, we'll explore how to pass a wide string from Python to a C function that requires a wchar_t** argument.

Passing a Wide String to a C Library Function Accepting wchar_t**

1. Import the ctypes Module

Start by importing the ctypes module:

2. Define the C Function

Assume you have a C function that takes a wchar_t** argument. Below is an example of such a function:

Compile this C code into a shared library (e.g., example.so on Linux or example.dll on Windows).

3. Load the Shared Library

Load the shared library in your Python code:

4. Define the Argument Types

Next, define the argument types for the C function, specifying that it expects a pointer to a pointer of wide characters (wchar_t**):

5. Prepare the Wide String Data

To pass a wide string (or an array of wide strings) to the C function, create an array of c_wchar pointers. Here’s how to do that:

6. Call the C Function

Now you can call the C function, passing the array of wide strings and the count:

7. Full Example

Here’s the complete code that illustrates the entire process:

Conclusion

Passing a wide string (or an array of wide strings) to a C library function that accepts wchar_t** can be easily achieved in Python using the ctypes module. By defining the function's argument types, preparing your wide string data, and calling the function with the appropriate arguments, you can effectively interface with C libraries from Python. This capability enables the use of existing C code that works with wide characters within your Python applications.