Regex for PascalCased words (aka camelCased with leading uppercase letter)

user_25068 0
Viewed 51533

How do I find all PascalCased words in a document with a regular expression?

If you don't know the word Pascal cased, I'm only concerned with leading Upper camel case (i.e., camel cased words in which the first letter is capitalized).

pascalcasing camelcasing search regex
9 Answers
([A-Z][a-z0-9]+)+

Assuming English. Use appropriate character classes if you want it internationalizable. This will match words such as "This". If you want to only match words with at least two capitals, just use

([A-Z][a-z0-9]+){2,}

UPDATE: As I mentioned in a comment, a better version is:

[A-Z]([A-Z0-9]*[a-z][a-z0-9]*[A-Z]|[a-z0-9]*[A-Z][A-Z0-9]*[a-z])[A-Za-z0-9]*

It matches strings that start with an uppercase letter, contain only letters and numbers, and contain at least one lowercase letter and at least one other uppercase letter.

user_254980

Adam Crume's regex is close, but won't match for example IFoo or HTTPConnection. Not sure about the others, but give this one a try:

\b[A-Z][a-z]*([A-Z][a-z]*)*\b

The same caveats as for Adam's answer regarding digits, I18N, underscores etc.

You can test it out here.

user_1189030

This seems to do it:

/^[A-Z][a-z]+([A-Z][a-z]+)+/

I've included Ruby unit tests:

require 'test/unit'

REGEX = /^[A-Z][a-z]+([A-Z][a-z]+)+/

class RegExpTest < Test::Unit::TestCase
  # more readable helper
  def self.test(name, &block)
    define_method("test #{name}", &block)
  end

  test "matches camelcased word" do
    assert 'FooBar'.match(REGEX)
  end

  test "does not match words starting with lower case" do
    assert ! 'fooBar'.match(REGEX)
  end

  test "does not match words without camel hump" do
    assert ! 'Foobar'.match(REGEX)
  end

  test "matches multiple humps" do
    assert 'FooBarFizzBuzz'.match(REGEX)
  end
end
nakajima_395890 
([A-Z][a-z\d]+)+

Should do the trick for upper camel case. You can add leading underscores to it as well if you still want to consider something like _IsRunning upper camel case.

user_849420

Pascal Case - no digits allowed


    ^[A-Z](([a-z]+[A-Z]?)*)$

Test Cases: https://regex101.com/library/sF2jRZ

Pascal Case - digits allowed


    ^[A-Z](([a-z0-9]+[A-Z]?)*)$

Test Cases: https://regex101.com/library/csrkQw

Pascal Case - digits allowed - Upto 3 upper case letters

To support 2-3 letter capitalized acronyms such as IOStream, StreamIO, DeviceID, deviceID, AwsVPC, awsVPC, serialNO, SerialNO, deviceSN, DeviceSN. This variation is inspired by Microsoft's Capitalization Convention.


    ^[A-Z](([A-Z]{1,2}[a-z0-9]+)+([A-Z]{1,3}[a-z0-9]+)*[A-Z]{0,3}|([a-z0-9]+[A-Z]{0,3})*|[A-Z]{1,2})$

Test Cases: https://regex101.com/library/TLTXbK

For more details on camel case and pascal case check out this repo.

user_2151200
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