RegexOne - Learn Regular Expressions - Problem 6: Trimming whitespace from start and end of line

Problem 6: Trimming whitespace from start and end of line

Occasionally, you'll find yourself with a log file that has ill-formatted whitespace where lines are indented too much or not enough. One way to fix this is to use an editor's search a replace and a regular expression to extract the content of the lines without the extra whitespace.

We have previously seen how to match a full line of text using the hat ^ and the dollar sign $ respectively. When used in conjunction with the whitespace \s, you can easily skip all preceding and trailing spaces.

Write a simple regular expression to capture the content of each line, without the extra whitespace.

Exercise 6: Matching lines

Task	Text	Capture Groups
capture	The quick brown fox...	The quick brown fox...
capture	jumps over the lazy dog.	jumps over the lazy dog.

Solution

We can just skip all the starting and ending whitespace by not capturing it in a line. For example, the expression ^\s*(.*)\s*$ will catch only the content.

Solve the above task to continue on to the next problem, or read the Solution.

Lesson Notes

	abc…	Letters
	123…	Digits
	\d	Any Digit
	\D	Any Non-digit character
	.	Any Character
	\.	Period
	[abc]	Only a, b, or c
	[^abc]	Not a, b, nor c
	[a-z]	Characters a to z
	[0-9]	Numbers 0 to 9
	\w	Any Alphanumeric character
	\W	Any Non-alphanumeric character
	{m}	m Repetitions
	{m,n}	m to n Repetitions
	*	Zero or more repetitions
	+	One or more repetitions
	?	Optional character
	\s	Any Whitespace
	\S	Any Non-whitespace character
	^…$	Starts and ends
	(…)	Capture Group
	(a(bc))	Capture Sub-group
	(.*)	Capture all
	(abc\|def)	Matches abc or def