convert unstructured data to structured data?

Question

How can I convert unstructured data into structured data? For example email contacts, from an unstructured text, to a structured format.

Are there any algorithms to do this?

Answer 1

There's no generic algorithm to "take unstructured data and convert it to structured data", no. It's highly dependent on what the possible range of input is, and what the desired structure is, and what conversions need to be applied, etc.

The class of problem is called "parsing": you need to construct a parser for the specific inputs you expect, and use that parser to generate structure from what it discovers about the input you get.

Your programming language will likely have parsing libraries available to assist with constructing a specific parser.