C++ Locale Library - isdigit

Description

It checks if character is decimal digit.

Declaration

Following is the declaration for std::isdigit.

C++98

int isdigit ( int c );

C++11

int isdigit ( int c );

Parameters

c − Character to be checked, casted to an int, or EOF.

Return Value

It returns a value different from zero.

Exceptions

No-throw guarantee − this function never throws exceptions.

Example

In below example for std::isdigit.

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
int main () {
   char str[]="2016ad";
   int year;
   if (isdigit(str[0])) {
      year = atoi (str);
      printf ("The year that followed %d was %d.\n",year,year+1);
   }
   return 0;
}

The sample output should be like this −

 The year that followed 2016 was 2017.