1295. Find Numbers with Even Number of Digits (easy)

Q:

Given an array nums of integers, return how many of them contain an even number of digits.

Example 1:

Input: nums = [12,345,2,6,7896]
Output: 2
Explanation: 
12 contains 2 digits (even number of digits). 
345 contains 3 digits (odd number of digits). 
2 contains 1 digit (odd number of digits). 
6 contains 1 digit (odd number of digits). 
7896 contains 4 digits (even number of digits). 
Therefore only 12 and 7896 contain an even number of digits.

Example 2:

Input: nums = [555,901,482,1771]
Output: 1 
Explanation: 
Only 1771 contains an even number of digits.

Constraints:

• 1 <= nums.length <= 500
• 1 <= nums[i] <= 10^5

A:

class Solution {
public:
    int findNumbers(vector<int>& nums) {
        int res=0; 
        for(auto v : nums)
        {
            string s = to_string(v);
            if(s.length() %2==0)
                res++;
        }
        return res;
    }
};

Learned:
int res;  如果不显示声明为0， 的话，会有奇怪的结果。  in method, no default value.