问题:统计某个给定范围[L, R]的所有整数中,数字2出现的次数。
#include <cstdio>
#include <iostream>
#include <cstring>
#include <cstdlib>
using namespace std;
char s[10];
int main()
{
int l, r, ans = 0;
cin >> l >> r;
for (int i = l; i <= r; ++i) {
sprintf(s, "%d", i);
int len = strlen(s);
for (int j = 0; j <= len - 1; j++)
if(s[j] = '2')
++ans;
}
cout << ans;
system("pause");
return 0;
}