1CTYPE(3) Library Functions Manual CTYPE(3)
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3
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6 isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace,
7 ispunct, isprint, isgraph, iscntrl, isascii, toupper, tolower, toascii
8 - character classification macros
9
11 #include <ctype.h>
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13 isalpha(c)
14
15 . . .
16
18 These macros classify ASCII-coded integer values by table lookup. Each
19 is a predicate returning nonzero for true, zero for false. Isascii and
20 toascii are defined on all integer values; the rest are defined only
21 where isascii is true and on the single non-ASCII value EOF (see
22 stdio(3S)).
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24 isalpha c is a letter
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26 isupper c is an upper case letter
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28 islower c is a lower case letter
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30 isdigit c is a digit
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32 isxdigit c is a hex digit
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34 isalnum c is an alphanumeric character
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36 isspace c is a space, tab, carriage return, newline, vertical
37 tab, or formfeed
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39 ispunct c is a punctuation character (neither control nor
40 alphanumeric)
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42 isprint c is a printing character, code 040(8) (space) through
43 0176 (tilde)
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45 isgraph c is a printing character, similar to isprint except
46 false for space.
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48 iscntrl c is a delete character (0177) or ordinary control char‐
49 acter (less than 040).
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51 isascii c is an ASCII character, code less than 0200
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53 tolower c is converted to lower case. Return value is undefined
54 if not isupper(c).
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56 toupper c is converted to upper case. Return value is undefined
57 if not islower(c).
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59 toascii c is converted to be a valid ascii character.
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62 ascii(7)
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667th Edition May 12, 1986 CTYPE(3)