how determine if a string has digits in c++ code example

Example 1: how to find how many digits a number has in c++

#include <iostream>
#include <cmath>

unsigned int getNumberOfDigits (int i)
{
    return i > 0 ? log10((double) i) + 1 : 1;
}

int main()
{
	std::cout << "Number of digits: " << getNumberOfDigits(/*Example*/6738) << std::endl;  
	return 0;
}

Example 2: check if character in string is digit c++

#include<stdio.h>
#include<ctype.h>

int main() {
   char val1 = 's';
   char val2 = '8';

   if(isdigit(val1))
   printf("The character is a digit\n");
   else
   printf("The character is not a digit\n");

   if(isdigit(val2))
   printf("The character is a digit\n");
   else
   printf("The character is not a digit");

   return 0;
}