What will happen when we access the ' Length ' property of string in C#?

Question

The sample code like this:

string hi = "HelloWorld";
int length = hi.Length;
Console.WriteLine(length);
Console.WriteLine(length);
...

string hi = "HelloWorld";
int length = hi.Length;
Console.WriteLine(hi.Length);
Console.WriteLine(hi.Length);
...

If the Length property of string will be accessed more than once, is the first snippet code better than the second? Why?

When we access the length of string in the way of hi.Length, the CLR will count the number of character in hi and return it or just return a 10 cause the Length property has been assigned a value of 10 at the time hi is initialized or something else?

How about in Java?

Answer 1

Length is a property of an array (string is an array of characters internally) which means it's always already available in memory (an array is always fixed length so the Length property won't change). In both cases you should always just use hi.Length instead of declaring another variable. Now you are just saving the length twice in memory (once on the stack for the int and once on the heap for the property).

Edit: As commenters below have pointed out, this method is optimised for ICollection to use the property instead of iterating. If you were to use the linq method .Count(), this would cause your program to iterate over the entire array to count the elements.