Use of slice grammar sugar in C ＃

Example

First, let's look at an example , There is such an array

string [] lst = new string[] { "1", "2", "3", "4", "5", "6", "7" };

How do we get its last value , The traditional method is written like this ,

string str = lst[lst.Length-1];

How to write slice grammar sugar ？

string str = lst[^1];

If you write like this , There's no difference between the two lines of code , It doesn't show the advantages of slice grammar sugar .

So if we extract index=1,2,3 What about the data? , The traditional practice is like this

var temp = new string【】 { lst[1], lst[2], lst[3] };

Or right linq More familiar students will write like this

var temp = lst.Skip(1).Take(3).ToArray();

Here I'd like to talk about skip and take What does that mean?

•Skip Is to skip the first few elements , Start getting the contents of the subscript value •Take Is to get the values of several elements ,

But if we slice, the operation is too simple

var temp = lst[1..3];

Let's run the code , Why , How can I only get two , Let's look at the official definition ,

End Gets a range that does not contain the end index Index.

What does this mean , That little friend who is familiar with high school mathematics collection should know , there 1..3 It's actually the one in our collection 1 To 3 Left closed right away , It's written like this in mathematics [1,3), Then we need to get the first three elements , It should be written as [1,4)(1 To 4 Left closed right away ), The code to

var temp = lst[1..4];

Through these two examples, you should learn c# Slice grammar sugar in ,

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