Conditional string.FormatConditional string.Format:
Applies different formatting to a number depending on whether the number is positive, negative, or zero.
string s = string.Format("{0:positive;negative;zero}", i); e.g.
string format = "000;-#;(0)"; string pos = 1.ToString(format); // 001 string neg = (-1).ToString(format); // -1 string zer = 0.ToString(format); // (0)