C :

#include<math.h>
#include <stdio.h>
int sum[10000]={0};
int count(int n)
{
	int x=0;
	while(n)
	{	
		if(n%10==2)x++;
		n/=10;
	}
	return x;
}
void main()
{ 
	int i;
	int s,t;	
	for(i=0;i<10001;i++)
	{	
		sum[i]=count(i);
		sum[i]+=sum[i-1];
	}
	while(scanf("%d%d",&s,&t)!=EOF)
	{	
		printf("%d\n",sum[t]-sum[s-1]);
	}
}

C++ :

#include <iostream>
#include <cstdio>
using namespace std;

int main()
{
	int l,r;
	char buf[10];
	int two = 0;
	cin >> l >> r;
	for(int i=l; i<=r; ++i)
	{
		int len = sprintf(buf,"%d",i);
		for(int j=0; j<len; ++j)
		{
			if(buf[j] == '2')
				two++;
		}
	}
	cout << two << endl;
	return 0;
}

Pascal :

var  l,r,i,n,t:integer;
begin
   while not(eof) do
   begin
     t:=0;
     readln(l,r);
     for i:=l to r do
     begin
       n:=i;
       while n>0 do
       begin
         if n mod 10=2 then inc(t);
         n:=n div 10;
       end;
     end;
     writeln(t);
   end;
end.

Java :

import java.util.Scanner;


public class Main {

	static int  Count(int num,int find){
		String strNum = num+"";
		String strFind = find+"";
		int fromIndex = 0;
		int count = 0;
		while(true){
			int pos = strNum.indexOf(strFind, fromIndex);
			if(pos != -1){
				fromIndex=pos+1;
				count++;
			}
			else
				break;
		}
		return count;
		
	}
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int find = 2;
		int count = 0;
		while(s.hasNext()){
			int L = s.nextInt();
			int R = s.nextInt();
			for(int i=L;i<=R;i++){
				count += Count(i,find);
			}
			System.out.println(count);
			count = 0;
		}

	}

}