How to check whether string contains any element present in the string array

Question

string str = "cat:fox";
string[] strArr = new string[] { "cat", "dog" };

I have a string like str. I need to check whether that string contains any element present in the strArr like exactly "cat" or "dog".

If the string is "cat:fox" method should returns true. If the string is "dog:fox" method should returns true.

The thing I tried was:

string[] split = str.Split(':');
blnReturn = false;

foreach (var item in split)
{
  foreach(var item1 in strArr)
  {
    if(item == item1)
       blnReturn = true;
  }
}

Note :- Meaning is values are concatenated with colon.I need to check whether that string contains any value present in the strArr.

How to do this better?

UPDATE

Requirement is if str is str = "cat dfgfg:fox"; It should not return true. Only it should be cat.

Otherwise we can check this way strData = str.Split(':'); and strArr is already there.

Condition is any one data in strArr (string array) should match with strData (string array) then it should return true.

What's wrong with this code you wrote?

Vahid Nateghi
– Vahid Nateghi

2013-11-12 08:04:55 +00:00
Commented Nov 12, 2013 at 8:04 — Vahid Nateghi
– Vahid Nateghi, Commented Nov 12, 2013 at 8:04

Community · Accepted Answer · 2017-05-23 12:19:11Z

3

Looks like you can use Enumerable.Any method like;

string str = "cat:dog";
string[] strArr = new string[] { "cat", "dog" };

if (strArr.Any(str.Contains))
{
  // Your string contains one the array values
}

Of course this works also cats, catss and cat:asdasd:dog becuase of the Contains definition.

You didn't mentioned but if you don't want to match string like cat:asdasd dog check out Marc Gravell's answer which looks the correct one.

edited May 23, 2017 at 12:19

CommunityBot

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answered Nov 12, 2013 at 8:05

Soner Gönül

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3 Comments

Anirudha Over a year ago

though that would match cats instead of matching only cat

Marc Gravell Over a year ago

that has edge-cases, though; should "cat:prairie dog" be a match? in your code it will; in the original code, it won't

Soner Gönül Over a year ago

@MarcGravell You are right. To be honest, I didn't look too much OP's code becuase he wants to get If the string is "cat:fox" method should returns true. If the string is "dog:fox" method should returns true.

helb · Accepted Answer · 2013-11-13 07:33:21Z

2

If you want to distinguish between "cat" and "cats" you better do:

bool Match(string str, string[] strArr)
{
    return strArr.Intersect(str.Split(':')).Any();
}

edited Nov 13, 2013 at 7:33

answered Nov 12, 2013 at 8:07

helb

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2 Comments

Jim Mischel Over a year ago

Rather than .Count() > 0, use .Any(). The reason is that Count() requires that the entire list be enumerated whereas .Any() will stop as soon as one is found.

helb Over a year ago

@JimMischel I updated my answer. I appreciate it if people think about performance when using Linq.

Marc Gravell · Accepted Answer · 2013-11-12 08:11:35Z

In most circumstances, the code you post is fine. If you need to minimize allocations (because it is a tight loop), so don't want to Split, you can use something like:

public static bool ContainsToken(string value, string token, char delimiter = ';')
{
    if (string.IsNullOrEmpty(token)) return false;
    if (string.IsNullOrEmpty(value)) return false;

    int lastIndex = -1, idx, endIndex = value.Length - token.Length, tokenLength = token.Length;
    while ((idx = value.IndexOf(token, lastIndex + 1)) > lastIndex)
    {
        lastIndex = idx;
        if ((idx == 0 || (value[idx - 1] == delimiter))
            && (idx == endIndex || (value[idx + tokenLength] == delimiter)))
        {
            return true;
        }
    }
    return false;
}

then something like:

static bool ContainsAnyOf(string value, string values)
{
    for(int i = 0 ; i < strArr.Length; i++)
    {
        if(ContainsToken(values, value, ':')) return true;
    }
    return false;
}

Konrad Kokosa · Accepted Answer · 2013-11-12 08:06:29Z

0

You can use LINQ:

bool contains = strArr.Any(pattern => str.Contains(pattern));

answered Nov 12, 2013 at 8:06

Konrad Kokosa

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Comments

Abbas · Accepted Answer · 2013-11-12 08:09:53Z

0

This should do the trick, you don't have to split the original string and create a double loop:

foreach(string s in array)
    if(word.Contains(s))
        return true;
return false;

In a method:

public bool ContainsItem(string word, string[] array)
{
    foreach(string s in array)
        if(word.Contains(s))
            return true;                
    return false;
}

//Usage:
var result = ContainsItem(str, strArr);

Or you can use the Enumerable Any() method:

var result = strArr.Any(s => str.Contains(s));

answered Nov 12, 2013 at 8:09

Abbas

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Comments

Stefan · Accepted Answer · 2013-11-12 08:10:16Z

0

You could also use a List instead of an Array:

string str = "cat:fox";
List<String> animallist = new List<String>();

animallist.add("cat");
animallist.add("dog");

//Now you can check like

if(animallist.Contains("cat")){

   //do something

}

answered Nov 12, 2013 at 8:10

Stefan

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Comments

user338195 · Accepted Answer · 2013-11-12 08:31:06Z

0

var str = "cat:fox";
var strArr = new[] { "cat", "dog" };

var result = strArr.ToList().Where(str.Contains);

First element of result will contain 'cat'

answered Nov 12, 2013 at 8:31

user338195

Comments

Anirudha · Accepted Answer · 2013-11-12 08:31:18Z

0

Your attempt is correct!

Though if you a have very large string separated by : and you want to perform look up operations quite frequently you can use dictionary since it's Contains method is O(1) and so is very fast!

var dictionary=str.Split(new char[]{':'})
                  .ToDictionary(x=>x,x=>"");
bool contains=strArr.Any(x=>dictionary.ContainsKey(x));//fast ops

edited Nov 12, 2013 at 8:31

answered Nov 12, 2013 at 8:11

Anirudha

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