Difference between string. Empty, "" and null

String. Empty field

. NET Framework class library

Represents an empty string. This field is read-only. Namespace: System

Assembly: mscorlib (in mscorlib. dll)

Protected string loginid = string. Empty;

Protected string loginid = "";

String. Empty does not allocate storage space

"" Allocate a bucket with an empty Length

Therefore, we generally use string. Empty

For the sake of future cross-platform use string. Empty

In C #, "" And string. Empty Can be used interchangeably. For example:

String S = "";

String S2 = string. empty;

If (S = string. Empty ){

//

}

If statement is true

Several methods for determining as a Null String, in the order of performance from high to low:

S. Length = 0 is better than S = string. Empty is better than S = ""

About string. the problem with empty and null is that both of them indicate null strings, and one of them focuses on string str1 = string. the difference between empty and string str2 = NULL. After this definition, str1 is an empty string, and the empty string is a special string, except that the value of this string is null, in the memory, there is an accurate point. String str2 = NULL. After this definition, only a reference to the string class is defined, and str2 does not point to any place, if it is not instantiated before use, an error will be reported. Textbox1.text is a zero-length string "".

Can it be understood as follows:
String. Empty does not allocate storage space. The value is null;

"" An Empty storage space is allocated. The value is null;
Null does not allocate storage space and has no value.