Okay in the previous post we had found the “find” tool and realised we can do so much more with it using regular expressions (regEx).
To recap a regEx is
“a sequence of symbols and characters expressing a string or pattern to be searched for within a longer piece of text.”
\d = a character 0 to 9
\w = any character a to Z and 0 to 9
\s = whitespace
Example:
\d\d\d will (using the find tool in your text editor) will highlight groups of 3 numbers in a string
\w\w\w\w\w will highlight groups of 5 characters
Notice how \w\w\w included numbers and letters
\s\s will highlight double spaces
Lets look for words that have only 4 characters.
A 4 letter word can be described as,
“a space followed by any 4 characters, followed by a space”
\s\w\w\w\w\s
Which can be rewritten as
\s\w{4}\s
But that will also include numbers. To ignore numbers
\s\w{4}[a-z]\s
Not quite there, if you are playing along you will notice that we are highlighting 4 letter words and the space before and after. What we need is to set boundaries.
\b\w{4}[a-z]\b
\b is a boundary, there are a few but for now lets stay with ‘spaces’. So with that you can find all four letter words
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