Regular Expression Examples

Below are given some examples of using regular expressions in various situations.

Find any HTML colour constant.

Find pattern

\#{[0-9A-Fa-f]}+

Replace all HTML colour constants with the new one (#AFEEEE).

Find pattern	\#{[0-9A-Fa-f]}+
Replace pattern	#AFEEEE

Replace all occurences of full stop before the lowercase letter with comma, truncating separating spaces to only one (useful for scanned documents).

Find pattern	{\.\s#}(\L[a-z])
Replace pattern	\, \1

Strip HTML tags.

Find pattern	{\<}{\/?}{.#}{\>}
Replace pattern	empty

Change the value of all "background-color:" CSS properties everywhere.

Find pattern	(background\-color\:){\#{[0-9A-Fa-f]}+}
Replace pattern	\1#FFE4E1

Replace <P> tags with <DIV> tags, preserving tag attributes.

Find pattern	\<P\s(.#)\>(.#)\<\/P\>
Replace pattern	<DIV \1>\2</DIV>

Colorize HTML tags for use inside HTML page: symbols with blue, tag with red, convert < and > to entities.

Find pattern	\<({\/}?)(.#)\>
Replace pattern	<span style="color:blue">&lt;\1</span><span style="color:red">\2</span><span style="color:blue">&gt;</span>

Find host addresses.

The pattern would match the following:

• http://www.host.dom/
• http://host.dom/
• ftp://203.131.69.75/
• www.host.dom/

Find pattern	({ht}|{f}tp\:\/\/)?{[0-9]#\.[0-9]#\.[0-9]#\.[0-9]#}|{{[^\.\/]#\.}?{[^\.\/]#\.[^\.\/]#}}\/
Replace pattern

Find the whole paragraph; store the paragraph contents.

Find pattern	(.#){\r\n}|{{\r}|{\n}}
Replace pattern