1ISALPHA(3)                 Linux Programmer's Manual                ISALPHA(3)
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NAME

6       isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower,
7       isprint, ispunct, isspace, isupper, isxdigit - character classification
8       routines
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SYNOPSIS

11       #include <ctype.h>
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13       int isalnum(int c);
14       int isalpha(int c);
15       int isascii(int c);
16       int isblank(int c);
17       int iscntrl(int c);
18       int isdigit(int c);
19       int isgraph(int c);
20       int islower(int c);
21       int isprint(int c);
22       int ispunct(int c);
23       int isspace(int c);
24       int isupper(int c);
25       int isxdigit(int c);
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DESCRIPTION

28       These  functions  check  whether  c,  which  must  have the value of an
29       unsigned char or EOF, falls into a certain character class according to
30       the current locale.
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32       isalnum()
33              checks for an alphanumeric character; it is equivalent to (isal‐
34              pha(c) || isdigit(c)).
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36       isalpha()
37              checks for an alphabetic character; in the standard "C"  locale,
38              it  is  equivalent  to  (isupper(c)  ||  islower(c)).   In  some
39              locales, there may be additional characters for which  isalpha()
40              is true—letters which are neither upper case nor lower case.
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42       isascii()
43              checks  whether  c is a 7-bit unsigned char value that fits into
44              the ASCII character set.
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46       isblank()
47              checks for a blank character; that is, a space or a tab.
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49       iscntrl()
50              checks for a control character.
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52       isdigit()
53              checks for a digit (0 through 9).
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55       isgraph()
56              checks for any printable character except space.
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58       islower()
59              checks for a lower-case character.
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61       isprint()
62              checks for any printable character including space.
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64       ispunct()
65              checks for any printable character which is not a  space  or  an
66              alphanumeric character.
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68       isspace()
69              checks  for  white-space  characters.   In  the  "C" and "POSIX"
70              locales, these are: space,  form-feed  ('\f'),  newline  ('\n'),
71              carriage  return ('\r'), horizontal tab ('\t'), and vertical tab
72              ('\v').
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74       isupper()
75              checks for an uppercase letter.
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77       isxdigit()
78              checks for a hexadecimal digits, i.e. one of
79              0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F.
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RETURN VALUE

82       The values returned are non-zero if the  character  c  falls  into  the
83       tested class, and a zero value if not.
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CONFORMING TO

86       C99, 4.3BSD.  C89 specifies all of these functions except isascii() and
87       isblank().  isascii() is a BSD extension and is also an SVr4 extension.
88       isblank() conforms to POSIX.1-2001 and C99 7.4.1.3.
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NOTE

91       The  details  of  what characters belong into which class depend on the
92       current locale.  For example, isupper() will not recognize an  A-umlaut
93       (Ä) as an uppercase letter in the default C locale.
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SEE ALSO

96       iswalnum(3),  iswalpha(3),  iswblank(3), iswcntrl(3), iswdigit(3), isw‐
97       graph(3), iswlower(3), iswprint(3),  iswpunct(3),  iswspace(3),  iswup‐
98       per(3),  iswxdigit(3),  setlocale(3), tolower(3), toupper(3), ascii(7),
99       locale(7)
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103GNU                               1995-09-02                        ISALPHA(3)