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LowerCaseQ

Status: Stable

documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

Description

LowerCaseQ["string"]

Gives True if every character of "string" is a lowercase letter.

Examples (12)

Every input below was run against the current Mathilda build and its output recorded.

Basic examples (4)

In[1]:= LetterQ["αβγ"]
Out[1]= True

In[2]:= DigitQ["\:0662"]
Out[2]= False

In[3]:= UpperCaseQ["ABC"]
Out[3]= True

In[4]:= LowerCaseQ["abc1"]
Out[4]= False

Applications (8)

In[5]:= LowerCaseQ["hello"]
Out[5]= True

In[6]:= LowerCaseQ["Hello"]
Out[6]= False

A digit is not a lowercase letter

In[7]:= LowerCaseQ["abc1"]
Out[7]= False

The sharp s is lowercase, though it has no single uppercase form

In[8]:= LowerCaseQ["straße"]
Out[8]= True

In[9]:= LowerCaseQ["σοφία"]
Out[9]= True

In[10]:= Select[{"abc", "ABC", "Abc", "x y"}, LowerCaseQ]
Out[10]= {"abc"}

Runs of lowercase letters

In[11]:= StringCases["iPhone eBay", _?LowerCaseQ ..]
Out[11]= {"i", "hone", "e", "ay"}

Not a string: LowerCaseQ::string

In[12]:= LowerCaseQ[{"a"}]
Out[12]= LowerCaseQ[{"a"}]

Implementation notes

Algorithm. builtin_lowercaseq calls charq_builtin(res, "LowerCaseQ", CQ_LOWER), which requires one String argument (otherwise LowerCaseQ::string via strings_arg_message, unevaluated), then decodes the UTF-8 code points one at a time with u8_decode and returns False at the first one for which char_ok(CQ_LOWER, cp) fails — so the scan short-circuits — and True if none does (vacuously for ""). char_ok answers ASCII code points inline (a–z) and otherwise binary-searches k_lower_ranges with in_ranges. Inside a string pattern, predicate_class in string_pattern.c translates _?LowerCaseQ to the PCRE class [[:lower:]] instead of emitting a per-character callout.

Data structures. k_lower_ranges: sorted, disjoint code-point ranges of Unicode general category Ll, generated from Unicode 16.0.0 by tools/gen_unicode_tables.py.

Complexity / limits. O(L) for an ASCII string; otherwise O(L log R). Any non-letter (digit, space, punctuation) makes the result False. Characters are code points, not grapheme clusters. Not Listable; no packed-array or Compile[] surface (the argument is a String).

Attributes: Protected.

References

See also: LetterQ, DigitQ, UpperCaseQ

Notes & additional examples

Notes

  • True when every character is in Unicode category Ll (lowercase letter), using Unicode 16.0 ranges; True for "".
  • A non-string emits LowerCaseQ::string and stays unevaluated; not Listable.
  • See also: UpperCaseQ, ToLowerCase, LetterQ.