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isdigit |
Portability: | ISO/ANSI C conforming, UNIX compatible |
SYNOPSIS | |
DESCRIPTION | |
RETURN VALUE | |
CAUTION | |
EXAMPLE | |
RELATED FUNCTIONS | |
SEE ALSO |
SYNOPSIS |
#include <ctype.h> int isdigit(int c);
DESCRIPTION |
isdigit
tests an integer value to determine whether it is a numeric character (digit).
RETURN VALUE |
isdigit
returns 0 if the character is not a digit, or a nonzero value if it is. If
the argument is
EOF
, 0 is returned.
CAUTION |
The effect of
isdigit
on a noncharacter argument other than
EOF
is undefined. Do not assume that
isdigit
returns either 0 or 1.
EXAMPLE |
#include <ctype.h> #include <stdio.h> #define IDMAX 40 main() { char id[IDMAX+1]; char *text; char input[IDMAX]; int i; puts("Enter a string of numbers/characters (maximum 40):"); text = gets(input); /* Copy a string of digits from text to id. */ for (i = 0; i < IDMAX && isdigit(text[i]); ++i) id[i] = text[i]; id[i] = '\0'; /* Only the digits should be copied. */ printf("You first entered these digits: %s\n", id); }
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