1134: 字符串转换

#include<iostream>
#include<algorithm>
#include<cstring>

using namespace std ; 


#define maxn 120 
char str[maxn] ; 
int num ; 
int result = 0 ; 

int main(){
    num = 0 ; 
    cin>>str ; 
    for(int i=0 ; i<strlen(str) ; i++){
        if(isdigit(str[i])){
            result = result * 10 + str[i] - ‘0‘ ; 
        }
    }

    cout<<result*2<<endl ; 
    return 0 ; 
}