I find that the number of the solutions coded by C# is very small .So i write it.

```
public int LengthOfLongestSubstring(string s) {
char[] temp = s.ToCharArray();
int max = 0;
Dictionary<char,int> collection=new Dictionary<char,int>();
for (int i = 0, j = 0; i < temp.Length; i++)
{
if (collection.ContainsKey(temp[i]))
{
j = Math.Max(j, collection[temp[i]] + 1);
collection.Remove(temp[i]);
collection.Add(temp[i], i);
}
else
{
collection.Add(temp[i], i);
}
max = Math.Max(max, i - j + 1);
}
return max;
}
```