Difference between string S = NULL and string S = ""

String S = NULL;
Indicates an empty string that does not occupy space and does not open up space in the memory.

String S = "";
Open up space in the memory, but there is no value in the space ("" is also a string)
Indicates an empty string, which is listed in real form and occupies the memory space.

Null indicates an empty reference,
"" Indicates an empty string,

String. Empty is similar to "". 0 bytes are allocated in the memory.

If you want to declare a string variable whose initial value is null, you 'd better use string STR = string. empty;
 

Difference between string S = NULL and string S = ""