C Language: isdigit function
(Test for Digit)
In the C Programming Language, the isdigit function tests whether c is a digit.
Syntax
The syntax for the isdigit function in the C Language is:
int isdigit(int c);
Parameters or Arguments
- c
- The value to test whether it is a digit.
Returns
The isdigit function returns a nonzero value if c is a digit and returns zero if c is not a digit.
Required Header
In the C Language, the required header for the isdigit function is:
#include <ctype.h>
Applies To
In the C Language, the isdigit function can be used in the following versions:
- ANSI/ISO 9899-1990
isdigit Example
/* Example using isdigit by TechOnTheNet.com */ #include <stdio.h> #include <ctype.h> int main(int argc, const char * argv[]) { /* Define a temporary variable */ unsigned char test; /* Assign a test decimal digit character to the variable */ test = '7'; /* Test to see if this is a decimal digit character */ if (isdigit(test) != 0) printf("%c is a decimal digit character\n", test); else printf("%c is not a decimal digit character\n", test); /* Assign a non-digit character to the variable */ test = 'T'; /* Test to see if this is a decimal digit character */ if (isdigit(test) != 0) printf("%c is a decimal digit character\n", test); else printf("%c is not a decimal digit character\n", test); return 0; }
When compiled and run, this application will output:
7 is a decimal digit character T is not a decimal digit character
Similar Functions
Other C functions that are similar to the isdigit function:
See Also
Other C functions that are noteworthy when dealing with the isdigit function:
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