Sequential Combination of string from string

Question

I am stumped. I wanted to know if any combination in sequence order of the string is available. like for example my string to match is

string somevar = "rat";

then if an another string contains "rat", "at", "ra" or "r", "a", "t" it should return false.

I can only think of making condition for every single sequence i can manually find. but I am sure there could be some trick to find it easily. I had a look on Implement a function that prints all possible combinations of the characters in a string but it doesnt do what I want.

I am sorry if this is not very clear but I want to check a condition where

 if(somevar == "rat" || somevar == "at" || somevar == "ra" || somevar == "r" || somevar == "a" || somevar == "t")
 {
      \\do something
 }

Last edit invalidate previous requirement. You said "contains" earlier and now you directly compare with set of values. — Sinatr
– Sinatr, Commented Dec 14, 2016 at 9:12
@Sinatr: Yeah that was creating the confusion so i removed it. I mean to say. is my last condition should return false. Sorry for all the trouble — Mohit S
– Mohit S, Commented Dec 14, 2016 at 9:15
@mybirthname "drastically" - i just had to change a few characters — fubo
– fubo, Commented Dec 14, 2016 at 9:39
@fubo yes but few characters can change the question a lot. From contains to equal the difference is really big in my opinion. — mybirthname
– mybirthname, Commented Dec 14, 2016 at 9:40

Tim Schmelter · Accepted Answer · 2016-12-14 09:26:20Z

4

You don't need to check all substrings if it's sufficient that a single char is contained:

bool containsAnyChar = somevar.Intersect("rat").Any();

That works because a string implements IEnumerable<char>(is a collection of characters).

edited Dec 14, 2016 at 9:26

answered Dec 14, 2016 at 8:54

Tim Schmelter

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2 Comments

Tim Schmelter Over a year ago

@mybirthname: Any is less efficient if the string is large. It's just a loop so O(n), Intersect uses a set based aproach. If the string isn't large it doesn't matter anyway

mybirthname Over a year ago

@TimSchmelter yes I test it manually with 2 strings with 10k characters(1-10k numbers and 5k -15k numbers) and the difference is really big. I didn't know it, thanks for mention it like I said. I already upvoted you

fubo · Accepted Answer · 2016-12-14 12:28:07Z

3

You need a method that determines all substrings

public static IEnumerable<string> GetAllSubStrings(string input, int length)
{
    for (var i = 0; i < input.Length - length + 1; i++)
    {
        yield return input.Substring(i, length);
    }
}

then you can just create a list with all combintaions

string somevar = "rat";
List<string> subStrings = new List<string>();
for (int i = 0; i < somevar.Length; i++)
{
    subStrings.AddRange(GetAllSubStrings(somevar, i + 1));
}
// subStrings = {"rat", "at", "ra", "r", "a", "t"}

and finally check your other string against that list.

UPDATE to your updated Question:

//check "ra" 
string testItem = "ra";
bool contains = subStrings.Any(x => testItem == x);

edited Dec 14, 2016 at 12:28

answered Dec 14, 2016 at 8:45

fubo

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Comments

Manoj · Accepted Answer · 2016-12-14 09:19:29Z

-1

string somevar = "rat";
string anotherString = "rat is there";
bool result = somevar.ToCharArray().Any(ch => anotherString.Contains(ch));

answered Dec 14, 2016 at 9:19

Manoj

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