CODEWITHSUNDEEP
c#c#-4.0
SamIAm
SamIAm

Reputation: 2491

How to simplify an if statement String checking?

I have a method that takes a string and I would like to return true or false depending whether the string has been recorded previously.

So far I have it as follows:

string one = "abc";
string two = "def";
string three = "ghi";


MethodOne(string s)
{  
   if (s == one || s == two || s == three) 
       return true;
   else 
       return false;
 }

Now is there a simpler way to simplify this without using a lot of || and single string checking?

Would it better to put it in a string array and just use 

 if (array.contains(s))

or something similar where array is the list of strings to check against?

Upvotes: 0

Views: 124

Answers (5)

Alberto Solano
Alberto Solano

Reputation: 8227

Would it better to put it in a string array and just use

if (array.contains(s))

or something similar where array is the list of strings to check against?

Yes, it would be better to include all the strings you need to check against the string s into an array or a similar structure.

According to me, this is the best alternative to check the equality of your string, considering other strings because it improves a lot the readability. This form:

var arr = new[] {"abc", "def", "ghi"};
return arr.Contains(s);

is much more readable than:

if (s == one || s == two || s == three) 
       return true;
   else 
       return false;

Then this operation to another programmer will be clearer. Another reason to choose this form is that this will make the program easier to maintain in the future. What if you need to check your string against another string? You'll need only to insert another element into your array or collection, instead of checking another string in your if statement:

if (s == one || s == two || s == three || s == four)

It's clear that this statement will be difficult to maintain and very horrible to read.

About the collection to use, I think an array is enough for your task, but there are other good alternatives, such as a List<string> or a HashSet<string>, as pointed out by other users.

Upvotes: 0

user2160375
user2160375

Reputation:

If you know values at compile time or checking is dominating operation (rather than modyfing collection) consider BinarySearch. It performs checking in O(log n) time (Contains or Any takes O(n) - linear):

var arr = new[] {"abc", "def", "ghi"}; // could be static or const for example
return Array.BinarySearch(arr, s) >= 0;

Remember, that input array should stay sorted.

O(log n) is important when checking big collection. Here is sample table with comparsions.

Upvotes: 0

Selman Gen&#231;
Selman Gen&#231;

Reputation: 101701

If you want to compare a string with few other strings, you can simplify your code using a Collection e.g. an Array.Then you can check whether the string you are looking for is present in the array:

return  new [] { one, two, three }.Contains(s);

Another alternative would be using Any method:

return  new [] { one, two, three }.Any(x => x == s);

Ofcourse there are numerous ways to do that.But the main point is choosing the right data structure to simplify your code and keep it as simple and readable as possible.

Upvotes: 3

Luaan
Luaan

Reputation: 63742

You could also use a hashset if you're more concerned about speed and clarity than memory:

var hashSet = new HashSet<string> { "abc", "def", "ghi" };

hashSet.Contains("abc");

Upvotes: 2

Nikhil Agrawal
Nikhil Agrawal

Reputation: 48568

As you suggested best would be to create a collection and then check if value is present in it.

public bool MethodOne(string s)
{
    List<string> collection = new List<string>() {"abc", "def", "ghi"};

    return collection.Contains(s);
}

Upvotes: 0

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