10. What's wrong with this? string x = ""; for (int y = 0; y < 100; y++) { x += this.randomString(); } Strings are immutable objects in the CLR!
11. Use StringBuilder! string x = ""; StringBuilder y = new StringBuilder(); for (int i = 0; i < 100; i++) { y.Append(this.randomString()); } x = y.ToString();