How do spell checkers work

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". The Open Office Spell checker Hunspell can be a good starting point. Here is the Homepage: Hunspell at Sourceforge.

E James gives a great answer for how to tell if a word is valid. It probably depends on the spell checker for how they determine likely misspellings. One such method, and the one that I would use is the Levenshteinn String Similarity which looks at how many letters must be added, removed, or swaped in a word in order to make another word.

If you say spelled: Country as Contry. The levenshtein string similarity would be 1 since you have to only add 1 letter to transform contry into country. Determine those with the lowest levenshtein string similarity value, and then return the top X words that are most similar to the misspelled word. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. How do spell checkers work? Ask Question. Asked 12 years, 11 months ago. Active 10 months ago. Viewed 14k times. I'd kind of like to write this myself, tho I really don't know where to begin. Improve this question. A spellchecker works by searching for a given string in its dictionary of known strings. Any string not found in the dictionary is deemed an alleged misspelling.

To correct a misspelling, the spellchecker assumes that your misspelling must be a mutation of one of the strings in its dictionary. To suggest a correction, the spellchecker searches its dictionary for strings similar to the misspelling.

It then orders the potential corrections by their similarity and likelihood score. The known string nearest to your misspelling is the suggested correction.

Sometimes a correctly spelt and known string may itself require correction. Is a given word the most likely word in the current context? Did you really mean peanut allegory symptoms? Or is it more likely that you meant peanut allergy symptoms. But allegory is a legal English word! You intuitively know that the strings Penisilin and Penicillin are similar. So are Potato and Potatoe. Tomato and Potato are also similar.

The question is — how similar? How do you measure similarity? Is the string Potato closer to Potatoe or to Tomato? The measurement of string similarity is relevant to several disciplines, including Genetics. While similarity algorithms typically work with text strings, a string is merely a list of elements taken from some alphabet.

The F7 is the default shortcut key to start the spell check feature in Word and other programs that have spell checking features. While spell checkers are a great feature, always proofread what you've written before hitting the send, print, or post button.

A word may be spelled correctly but is not the word you intended to use. Although "spell check" is more common than "spellcheck" according to Google Trends, both versions are correct, and what version you use may depend on your style guide.

When used as a noun, you may describe the "spell check" or "spellchecker" feature found in a program. To get around this, add the lowercase word to the dictionary first. Keep in mind that adding a word adds it to whichever language dictionary you are using. That may be nice for the occasional borrowed term, but it will get overwhelming if you find yourself using a lot of foreign words not typically used in English vernacular. We will cover other language dictionaries later in this section.

You can switch your dictionary to a different language. Grammar check works much like spell check, searching through your document for grammatical and style errors rather than spelling errors.

Grammar check underlines words or phrases in blue or green, depending on your version of Word. Right-click on the underlined word or phrase to see suggested corrections. Like spell check, grammar check is prone to errors.