C# notes

1. string

Remember that string takes fixing memory until the program ends.

Null and Empty

In C#, a variable's value is null if it is not set, or if it has been explicitly set to null. A null value typically means the value is not known, or has not yet been set, and is frequently a source of errors in programs, because methods cannot be invoked on null instances of types. An empty string is simply a string with a length of zero. It's a valid instance of a string, but one that currently has no characters in it.

It shows how null can cause an exception. String.IsNullOrEmpty(emptyString) can help.

Some API:

Replacing Parts of Strings

The @:

Date and Time：

Refer to：Working with Dates and Times

Convert type：

Logical Expressions:

It is totally same as it is in C++.