C#完美化.Ch1.基本語言要素

這篇算是讀書心得, 稍微紀錄一下以免忘了

ref: 晉身世界第一流程式設計師：157個完美化C#的建議

1. 正確操作字串
1. String str1 = "str1" + 9;
2. String str2 = "str2" + 9.ToString();
2比1好, 不會發生裝箱行為


1. sring s1 = "abc";
   s1 = "123" + s1 + "456";
2. string s1 = "123" + "abc" + "456";
2比1好, 1需要在記憶體建立三個字串物件, 還執行string.Contact


1. string a = "t";a += "e";a += "s";a += "t";
   string result = a;
2. string a = "t";string b = "e";string c = "s";string d = "t";
   StringBuilder sb = new StringBuilder(a);
   sb.Append(b);sb.Append(c);sb.Append(d);
   string result = sb.ToString();
3. string a = "t";string b = "e";string c = "s";string d = "t";
   string result = string.Format("{0}{1}{2}{3}", a, b, c, d);
3=2 >>> 1, StringBuilder預設長度為16, 超過才會重新分配記憶體, string.Format內部使用StringBuilder




2. 使用預設的轉型方法