def c_str(string):
        """Create ctypes char * from a Python string.

        Parameters
        ----------
        string : string type
             Pyrhon string.

        Returns
        -------
        str : c_char_p
            A char pointer that can be passed to C API.

        Examples
        --------
        >>> x = c_str("Hello, world!")
        >>> print x.value
        Hello, world!
        """
        return ctypes.c_char_p(string)