题解 | #字符串中找出连续最长的数字串#

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

bool isNum(char ch)
{
    return ('0' <= ch && ch <= '9');
}

int main()
{
    string str;
    cin >> str;
    int begin = -1;
    int maxlen = -1;
    for(int i = 0;i< str.size();i++)
    {
        if(isNum(str[i]))
        {
            int j = i;
            while(j < str.size() && isNum(str[j]))
                j++;
            if(j -i > maxlen)
            {
                begin = i;
                maxlen = j-i;
            }
            i = j;
        }     
    }
    cout << str.substr(begin, maxlen) << endl;
    return 0;
}