Get all the values between lower and upper value

hello

i'm not sure, if question unique, couldn't find answer looking for.

want way values within lower value , upper value in c#, , want have list of values richtextbox1. 

example; lower value=apple28 , upper value=apple31. result this:

apple28

apple29

apple30

apple31

*if list have apple15 not in list because it's outside lower value , apple60 not in list because outside upper value. code load values within range list.

want code search values in external .txt file trough openfiledialog1 , values richtextbox1. not important, can find myself. need code find values within lower , upper value. 

know should try first believe me tried many times , failed. i new hope can show me.

regards

matthew's approach that.

or @ least think does, put version append in 1 statement.

why?

because like  messing code.

        private void button1_click(object sender, eventargs e)         {             if (openfiledialog1.showdialog() != dialogresult.ok) return;             string start = "apple28";             string end = "apple31";             richtextbox1.appendtext(                 string.join("",                 file.readlines(openfiledialog1.filename)                 .where(x => x.compareto(start) >= 0                     && x.compareto(end) <= 0)                 .select(x => x + "\n")                 .toarray()));         }

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hope helps.

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