力扣-1108题 IP地址无效化（C++）- string扩容

题目链接：https://leetcode-cn.com/problems/defanging-an-ip-address/
题目如下：

class Solution {
    
    
public:
    string defangIPaddr(string address) {
    
    
        int size=address.size();
        int new_size=size+3*2;
        address.resize(new_size);

        int pos=new_size-1;
        for(int i=size-1;i>=0;i--){
    
    
            if(address[i]!='.') address[pos--]=address[i];
            else {
    
    
                address[pos--]=']';
                address[pos--]='.';
                address[pos--]='[';
            }
        }

        return address;
    }
};