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UpperCaseQ

Status: Stable

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

Description

UpperCaseQ["string"]

Gives True if every character of "string" is an uppercase 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]:= UpperCaseQ["ABC"]
Out[5]= True

In[6]:= UpperCaseQ["AbC"]
Out[6]= False

A space is not an uppercase letter

In[7]:= UpperCaseQ["A B"]
Out[7]= False

Any script with case

In[8]:= UpperCaseQ["ΔΣÉ"]
Out[8]= True

Titlecase digraphs are category Lt, not Lu

In[9]:= UpperCaseQ["Dž"]
Out[9]= False

The 30 Latin-1 capitals, U+00C0-U+00DE minus ×

In[10]:= Length[Select[CharacterRange[192, 255], UpperCaseQ]]
Out[10]= 30

Capitalised words

In[11]:= StringCases["Hello World", _?UpperCaseQ ~~ (_?LowerCaseQ)..]
Out[11]= {"Hello", "World"}

In[12]:= UpperCaseQ[""]
Out[12]= True

Implementation notes

Algorithm. builtin_uppercaseq calls charq_builtin(res, "UpperCaseQ", CQ_UPPER), which requires one String argument (otherwise UpperCaseQ::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_UPPER, 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_upper_ranges with in_ranges. Inside a string pattern, predicate_class in string_pattern.c translates _?UpperCaseQ to the PCRE class [[:upper:]] instead of emitting a per-character callout.

Data structures. k_upper_ranges: sorted, disjoint code-point ranges of Unicode general category Lu, 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). Titlecase letters (Lt, such as Dž) are not uppercase; any non-letter 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, LowerCaseQ

Notes & additional examples

Notes

  • True when every character is in Unicode category Lu (uppercase letter); digits, spaces and punctuation make it False, so it is not "has no lowercase letters".
  • Titlecase letters (Lt, e.g. Dž) are neither upper- nor lowercase.
  • True for ""; a non-string emits UpperCaseQ::string. Not Listable.
  • See also: LowerCaseQ, ToUpperCase, LetterQ.