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Best way to get a substring when knowing the last index and how many characters to take before that in C#

byMR

October 7, 2022

Say I have a string abcdefghi

I would like to extract from that the string cdef

I know that the index of the last character I want is 5 (which is f).

I also know that I want to take the 3 preceding characters with it.

Here is my code so far, which does work, but doesn’t look that pretty. Is there a better way?

string text = "abcdefghi";
int lastIndex = 5;
int numberOfCharsToTake = 4  // including the last index char

Console.WriteLine(
    string.Join("",
    text
    .Substring(0, lastIndex + 1)
    .Reverse()
    .Take(numberOfCharsToTake)
    .Reverse()
    )
)

>Solution :

string text = "abcdefghi";
string lastIndex = 5;
string numberOfCharsToTake = 4  // including the last index char

Console.WriteLine(
    text.Substring(lastIndex - numberOfCharsToTake, numberOfCharsToTake)
);