Number of occurrences of 2 as a digit in numbers from 0 to n | C ++ program to count 2 s from 0 to n ; Counts the number of '2' digits in a single number ; Counts the number of '2' digits between 0 and n ; Initialize result ; Count 2 's in every number  from 2 to n ; Driver Code
#include <bits/stdc++.h> NEW_LINE using namespace std ; int number0f2s ( int n ) { int count = 0 ; while ( n > 0 ) { if ( n % 10 == 2 ) count ++ ; n = n / 10 ; } return count ; } int numberOf2sinRange ( int n ) { int count = 0 ; for ( int i = 2 ; i <= n ; i ++ ) count += number0f2s ( i ) ; return count ; } int main ( ) { cout << numberOf2sinRange ( 22 ) ; cout << endl ; cout << numberOf2sinRange ( 100 ) ; return 0 ; }