# Use the C-Language Implementation of the API

The C-language implementation of the Filter API is divided into the following function suites:

- File Extraction API Functions—Open and extract subfiles in a container file. These functions also extract metadata and file format information, and control character set conversion on extraction. The tstxtract sample program demonstrates these functions.
- Filter API Functions—Extract document information (metadata character set, format), create an input/output stream, and filter a file or stream. The filter sample program demonstrates these functions.

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