Extarct a list of strings based on another list of strings

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C#

List1: {"123456", "432978", "321675", …}  // containing 100,000 members

C#

List2: {"7674543897", "1234568897", "8899776644",…} // containing 50,000 members

I want to extract all items in List2 that their first 6 digits are from List1 members, so here the string “1234568897” is valid because its first 6 digits are from List1’s first item. What it the fastest way of doing this?

Posted 6-Mar-13 0:49am

hosseinrooholamini

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CHill60 6-Mar-13 6:55am

Given the number of members you suggest are in each list where are you getting these "strings" from ?

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Jegan Thiyagesan · Answer 1 · 2013-03-06T01:18:00

Hi,
you can achieve this as below:

C#

List<string> list1 = new List<string>();
list1.Add("123456");
list1.Add("432978");
list1.Add("321675");

List<string> list2 = new List<string>();
list2.Add("7674543897");
list2.Add("1234568897");
list2.Add("8899776644");

List<string> list3 = list2.FindAll(x => x.StartsWith(list1[0]));

So you have your first list that are the keys, and the second list that you are searching for and the third list that is the searched results.

Regards
Jegan