算法

a user entered an integer value into a text box. Without using a buit-in library, convert the numeric string to its integer representation.

static int StringTolnt(string s)
        {
            int sum = 0;
            for (int i = 0; i < s.Length; i++)
                sum = sum * 10 + (s[i] - '0');
            return sum;
        }