4.6.9 Random Access to Files

There are two methods of finding and setting the stream position, stream positioning and seeking. The current position of the read/write pointer in a specified stream can be obtained by using stream_position/2 or stream_property/2. It may be changed by using set_stream_position/2. Alternatively, seek/4 may be used.

Seeking is more general, and stream positioning is more portable. The differences between them are:

• stream_position/2 is similar to seek/4 with Offset = 0, and Method = current.
• Where set_stream_position/2 asks for stream position objects, seek/4 uses integer expressions to represent the position or offset. Stream position objects are obtained by calling stream_position/2, and are discussed in the reference page.