C ++ December notes

1. STD: String read on write mechanism, STD: string in the standard library. During the replication, the internal buffered string is not copied immediately, it is copied only when the string is edited. This is not described on C ++ primer. This reminds me of the C # string. All edits that cannot be modified on the string return a new string, similar to a string in Python, but Python caches small objects, small strings are directly cached to improve efficiency. The strings in Delphi are very similar to C ++'s STD: String. The first few strings are used to record the reference numbers of this string, when the string is edited, a copy is copied and a reference of the string is reduced. It seems that strings are processed a lot in each language and cannot be small. 2. Notes for using C ++ static variables. For this static object, the book describes how to store the common content of each object in the class, or record some content such as the number of generated objects, do not use other static variables during static variable initialization. I made a huge mistake here. reference the old saying: "Although static variables can be initialized before other variables, but the initialization sequence of static variables cannot be guaranteed. Note.