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isalnum
#include <ctype.h>
int isalnum (
int cval
);
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stand-alone
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Returns a non-zero value if cval is a letter or a digit, zero otherwise.
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isalpha
#include <ctype.h>
int isalpha (
int cval
);
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stand-alone
|
Returns a non-zero value if cval is a letter, zero otherwise.
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iscntrl
#include <ctype.h>
int iscntrl (
int cval
);
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stand-alone
|
Returns a non-zero value if cval is an ASCII control character (code < 20 , or code > 7F16), zero otherwise.
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isdigit
#include <ctype.h>
int isdigit (
int cval
);
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stand-alone
|
Returns a non-zero value if cval is one of the digits 0–9, zero otherwise.
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isgraph
#include <ctype.h>
int isgraph (
int cval
);
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stand-alone
|
Returns a non-zero value if cval is a printing character, codes 2116 ,('!') to 7E16 ('~') inclusive. Returns zero otherwise.
Note that this function treats the character values between 7F16 and FF16 inclusive as non-printable, although most are visible on a PC screen and on some printers.
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islower
#include <ctype.h>
int islower (
int cval
);
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stand-alone
|
Returns a non-zero value if cval is a lower-case letter, zero otherwise.
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isprint
#include <ctype.h>
int isprint (
int cval
);
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stand-alone
|
Returns a non-zero value if cval is a printing character, codes 2016 (space) to 7E16 ('~') inclusive. Returns zero otherwise.
Note that this function treats the character values between 128 and 255 inclusive as non-printable, although most are visible on a PC screen and on some printers.
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ispunct
#include <ctype.h>
int ispunct (
int cval
);
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stand-alone
|
Returns a non-zero value if cval is a punctuation character; otherwise zero. A punctuation character is defined as being any printing character (see isgraph) that is not a letter, a digit or a space.
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isspace
#include <ctype.h>
int isspace (
int cval
);
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stand-alone
|
Returns a non-zero value if cval is a space, horizontal or vertical tab, carriage return, newline or form feed character, zero otherwise.
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isupper
#include <ctype.h>
int isupper (
int cval
);
|
stand-alone
|
Returns a non-zero value if cval is an upper-case letter, zero otherwise.
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|
isxdigit
#include <ctype.h>
int isxdigit (
int cval
);
|
stand-alone
|
Returns a non-zero value if cval is a printing hexadecimal digit, zero otherwise. The printing hexadecimal digits are '0'–'9', 'a'–'f' and 'A'–'F'.
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