Regular expressions in MATLAB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of regular expressions in MATLAB?

Regular expressions in MATLAB are used to find, match, and manipulate text patterns within strings. They help automate searching and editing tasks.

beginner

Which MATLAB function is commonly used to find matches of a regular expression in a string?

The regexp function is used to find matches of a regular expression in a string and returns the starting indices of matches.

beginner

What does the regular expression pattern \d+ match in MATLAB?

The pattern \d+ matches one or more digits in a string. Here, \d means any digit (0-9), and + means one or more times.

intermediate

How do you extract the actual matched text using regexp in MATLAB?

Use the 'match' option with regexp like this: matches = regexp(str, pattern, 'match'); This returns the matched substrings themselves.

intermediate

What is the difference between regexp and regexpi in MATLAB?

regexp is case-sensitive when matching patterns, while regexpi performs case-insensitive matching.

Which MATLAB function returns the starting indices of matches for a regular expression?

A regexprep

B strfind

C regexp

D regexpi

regexp returns the starting indices of matches. regexprep replaces text, strfind finds substrings, and regexpi is case-insensitive regexp.

What does the regular expression ^abc match in a string?

A Any string containing 'abc'

B 'abc' at the start of the string

C 'abc' at the end of the string

D Any string ending with 'abc'

The caret ^ means the start of the string, so ^abc matches 'abc' only if it is at the beginning.

How do you perform a case-insensitive regular expression match in MATLAB?

A Use <code>regexpi</code>

B Use <code>strfind</code>

C Use <code>regexp</code> with 'ignorecase' option

D Use <code>regexprep</code>

regexpi performs case-insensitive matching directly.

What does the pattern \s represent in MATLAB regular expressions?

A Any digit

B Any special character

C Any letter

D Any whitespace character

\s matches any whitespace character like space, tab, or newline.

Which function would you use to replace text matching a regular expression in MATLAB?

A regexprep

B regexp

C regexpi

D strfind

regexprep replaces parts of a string that match a regular expression.

Explain how to find and extract all numbers from a string in MATLAB using regular expressions.

Think about how to match digits and get the actual text matched.

Describe the difference between regexp and regexpi in MATLAB and when you might use each.

Consider if you want to match text exactly or ignore letter case.