Character conversion PTA

This problem requires the extraction of all numeric characters in a string （'0'……'9'）, Convert it to an integer output .

Input format ：

The input gives no more than 80 Character string ending with carriage return .

Output format ：

Output the converted integer on one line . Ensure that the output does not exceed the long integer range .

sample input ：

#include <stdio.h>
int main(){
    char ch[81];
    int i=0,sum=0;
    while((ch[i]=getchar())!='\n'){
        if(ch[i]>='0'&&ch[i]<='9'){
            sum=sum*10+ch[i]-'0';
        }
        i++;
    }
    printf("%d",sum);
    return 0;
}

free82jeep5

sample output ：

825

Ideas ： Use it directly first putchar(), trouble , It's much simpler after changing to numerical value ;