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      islower

      From cppreference.com
      <c‎ |string‎ |byte
       
       
       
       
      Defined in header<ctype.h>
      int islower(int ch);

      Checks if the given character is classified as a lowercase character according to the current C locale. In the default "C" locale,islower returns true only for the lowercase letters (abcdefghijklmnopqrstuvwxyz).

      Ifislower returnstrue, it is guaranteed thatiscntrl,isdigit,ispunct, andisspace returnfalse for the same character in the same C locale.

      The behavior is undefined if the value ofch is not representable asunsignedchar and is not equal toEOF.

      Contents

      [edit]Parameters

      ch - character to classify

      [edit]Return value

      Non-zero value if the character is a lowercase letter, zero otherwise.

      [edit]Example

      Run this code
      #include <ctype.h>#include <locale.h>#include <stdio.h> int main(void){unsignedchar c='\xe5';// letter å in ISO-8859-1printf("In the default C locale,\\xe5 is %slowercase\n",           islower(c)?"":"not ");setlocale(LC_ALL,"en_GB.iso88591");printf("In ISO-8859-1 locale,\\xe5 is %slowercase\n",           islower(c)?"":"not ");}

      Possible output:

      In the default C locale, \xe5 is not lowercaseIn ISO-8859-1 locale, \xe5 is lowercase

      [edit]References

      • C23 standard (ISO/IEC 9899:2024):
      • 7.4.1.7 The islower function (p: TBD)
      • C17 standard (ISO/IEC 9899:2018):
      • 7.4.1.7 The islower function (p: 146)
      • C11 standard (ISO/IEC 9899:2011):
      • 7.4.1.7 The islower function (p: 202)
      • C99 standard (ISO/IEC 9899:1999):
      • 7.4.1.7 The islower function (p: 183)
      • C89/C90 standard (ISO/IEC 9899:1990):
      • 4.3.1.6 The islower function

      [edit]See also

      checks if a wide character is an lowercase character
      (function)[edit]
      ASCII valuescharacters

      iscntrl
      iswcntrl

      isprint
      iswprint

      isspace
      iswspace

      isblank
      iswblank

      isgraph
      iswgraph

      ispunct
      iswpunct

      isalnum
      iswalnum

      isalpha
      iswalpha

      isupper
      iswupper

      islower
      iswlower

      isdigit
      iswdigit

      isxdigit
      iswxdigit

      decimal hexadecimal octal
      0–8\x0–\x8\0–\10control codes (NUL, etc.)≠000000000000
      9\x9\11tab (\t)≠00≠0≠000000000
      10–13\xA–\xD\12–\15whitespaces (\n,\v,\f,\r)≠00≠0000000000
      14–31\xE–\x1F\16–\37control codes≠000000000000
      32\x20\40space0≠0≠0≠000000000
      33–47\x21–\x2F\41–\57!"#$%&'()*+,-./0≠000≠0≠0000000
      48–57\x30–\x39\60–\7101234567890≠000≠00≠0000≠0≠0
      58–64\x3A–\x40\72–\100:;<=>?@0≠000≠0≠0000000
      65–70\x41–\x46\101–\106ABCDEF0≠000≠00≠0≠0≠000≠0
      71–90\x47–\x5A\107–\132GHIJKLMNOP
      QRSTUVWXYZ      		0≠000≠00≠0≠0≠0000
      91–96\x5B–\x60\133–\140[\]^_`0≠000≠0≠0000000
      97–102\x61–\x66\141–\146abcdef0≠000≠00≠0≠00≠00≠0
      103–122\x67–\x7A\147–\172ghijklmnop
      qrstuvwxyz      		0≠000≠00≠0≠00≠000
      123–126\x7B–\x7E\173–\176{|}~0≠000≠0≠0000000
      127\x7F\177backspace character (DEL)≠000000000000
      Retrieved from "https://en.cppreference.com/mwiki/index.php?title=c/string/byte/islower&oldid=181276"
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