Null and string in C #. The difference between empty and equal space

Let's look at an effect chart first.

When you define only one str instead of allocating memory for it, use string str=null, but you must assign a value to it before you use it, such as str= "XXXX", which is initialized for it.
and string str= string. Empty is defined and initialized together it is actually equivalent to string str=null;str= "";
When used specifically, if you decide to assign a value to str before using string str=null, otherwise use string str= string. Empty, otherwise a null pointer exception may be thrown when the program is running

String. Empty does not allocate storage space
"" Allocates a storage space with an empty length
So you usually use string. Empty

In order to cross the platform later, or with String.Empty

In C #, most of the cases "" and string. Empty can be used interchangeably. Like what:

The code is as follows	Copy Code
string s = ""; String s2 = string. Empty; if (s = = string. Empty) { // }

If statement set up

Several ways to determine an empty string are in the order of performance from highest to lowest:

The code is as follows	Copy Code
S.length = 0 is superior to s = = string. Empty is superior to S = = ""

Your question about String.Empty and Null is this, both of which represent an empty string, with one focus on the difference between string str1= String.Empty and string str2=null, so that after the definition, str1 is an empty string, The empty string is a special string, except that the value of this string is null, and in memory there is an accurate point, string str2=null, so defined, just defines a reference to a string class, STR2 does not point to anywhere, if not instantiated before use, will have an error. The TextBox1.Text value is a zero-length string "".