The I2C C API can be used to communicate with telos I2C products within your own applications. This API supports the master mode of the I2C products. It is intended for developing small and simple applications. In case you are looking for an API that also supports the tracer or A/D mode please check the I2C C++ API or the I2C .NET API.
To get an impression of the I2C C API we recommend to download the manual, which contains the complete description of the API together with several examples.
You can download the C API as part of I2C Studio. The API can be tested even without a real I2C product as I2C Studio contains a virtual I2C product.