I need to implement a spell checker in C. Basically, I need all the standard operations... I need to be able to spell check a block of text, make word suggestions and dynamically add new words to the index.
I'd kind of like to write this myself, tho I really don't know where to begin.
Given you don't know where to begin, I'd suggest using an existing solution. See, for example, aspell (GLPL licenced). If you really have to implement it yourself, please tell us why.
There's a very interesting Python example and explanations there:
One should look at prefixes and suffixes.
suddenly = sudden + ly.
by removing ly's you can get away storing just the root word.
Likewise preallocate = pre + allocate.
And lovingly = love + ing + ly gets a bit more complex, as the english rules for ing get invoked.
There is also the possibility of using some sort of hashing function to map a root word into a specific bit is a large bit map, as a constant time method of determining if the root word is spelled correctly.
You can get even more complex by trying to provide an alternate list of possible correct spellings to a misspelled word. You might research the soundex algorithm to get some ideas.
I would advise prototyping with a small set of words. Do a lot of testing, then scale up. It is a wonderful educational problem.
Splitting a word into root and suffix is knonw as the "Porter Stemming Algorithm" it's a good way of fitting an English ditionary into an amazingly small memory.
It's also useful for seach so "spell checker" will also find "spelling check" and "spell checking"
I've done this in class
You should consider python Natural Language Toolkit NLTK which is made specificaly to handle this.
It also allows to create text interpreters such as chatbots
The Open Office Spell checker Hunspell can be a good starting point. Here is the Homepage: Hunspell at Sourceforge