```cpp
#include<bits/stdc++.h>
using namespace std;
int ge2(int i){
int ges2=0;
while(i!=0){
if(i%10==2) ges2++;
i /= 10;
}
return ges2;
}
int main()
{
int a , b,sum=0;
cin>>a>>b;
for(int i = a;i <= b;i++){
sum+=ge2(i);
}
cout<<sum;
return 0;
}
```
by isJason @ 2023-06-22 13:45:44
ges2初始值应为0
@[shenandy](/user/949311)
by isJason @ 2023-06-22 13:46:19
@[isJason](/user/738674) 谢谢
by shenandy1 @ 2023-06-22 19:50:49
```cpp
#include<bits/stdc++.h>
#include <cmath>
using namespace std;
int main()
{
int a,b,s=0;
cin>>a>>b;
for(int i=a;i<=b;i++){
int t=i;
for(int j=1;t>0;j++){
if(t%10==2){
s++;
}
t=t/10;
}
}
cout<<s;
return 0 ;
}
```
by yuwuyanqiu @ 2023-08-08 08:58:24
```
#include<iostream>
using namespace std;
int l,r,ans;
void lr(int x){
int y;
while(x){
y = x % 10;
x /= 10;
if(y == 2){
ans ++;
}
}
}
int main(){
cin >> l >> r;
for(int i = l ;i <= r;i ++){
lr(i);
}
cout << ans;
return 0;
}
```
by zqhbxsgs @ 2023-08-26 23:04:40
```cpp
#include <bits/stdc++.h>
using namespace std;
const int N=1e5+10;
int l,r;
int cnt=0;
int x;
int main(){
scanf("%d %d",&l,&r);
for(int i=l;i<=r;i++){
x=i;
while(x!=0){
cnt+=(x%10==2);
x/=10;
}
}
printf("%d",cnt);
return 0;
}
```
by littlesnake @ 2023-10-17 17:53:47