How to simplify an if condition having multiple OR cases [closed]

Answer 1

This is in addition to the suggestion to use an extension, but applies whether you do or not:

If you have a condition this long, you should isolate it in its own function, for example:

string GetCategory(string input)
{
    //all of your conditions
    return mySecondString;
}

Then in the method that used to contain this condition you just have the function call instead, like

var category = GetCategory(myString);

This does a few things:

• It makes the method that calls it more readable. Calling the function in a sense acts like a comment. Instead of having all of those conditions and wondering what it's for, they'll see the call to GetCategory and understand that you're getting the category. Similarly, when they look at the GetCategory function itself they'll understand what that code is for from the name of the function that it's in.
• It keeps the calling function shorter. 15 lines or less is a good recommendation. This condition itself is about that size, so separating it ensures that the calling function won't get too long.

Another suggestion - use constants, like

const string AliensVersusBovines = "AVB";

That prevents someone from reading this:

myString.Contains("AVB")

and wondering what "AVB" is, since it's not self-explanatory. If you're going to use that string in multiple classes (which seems likely) then you could create a separate class that just contains all of those constants. That keeps you from having the same string literal scattered throughout your code which can become a maintenance issue.

public class Codes
{
    public const string AliensVersusBovines = "AVB";
}

That way your code can read

myString.Contains(Codes.AliensVersusBovines)

Answer 2

Use an extension method:

public static bool ContainsAny(this string self, params string[] criteria)
{
    foreach (string s in criteria)
    {
        if (self.Contains(s))
        {
            return true;
        }
    }
    return false;
}

call it like this:

if (myString.ContainsAny("UCK", "SAN", "AVB", "AVM", "SDS", "DWW", "WQP", "LHG"))
{
    mySecondString = "CATEGORY A";
}

else if (myString.ContainsAny("UCT", "SAM", "AHJB", "AVR"))
{
    mySecondString = "CATEGORY B";
}

else if (myString.ContainsAny("UKC", "SHZ", "EEB"))
{
    mySecondString = "CATEGORY C";
}

else
{
    mySecondString = "CATEGORY D";
}

Answer 3

Best approach in my opinion is to use a Map (in Java) or Dictionary in C#:

class MyExample {
    // declaring your static map (should be private static final)
    private static Dictionary<String, String> myPreciousMap = new HashMap<>();

    public MyExample() {
        String categoryA = "CATEGORY A";
        String categoryX = "CATEGORY X"; // you know, A, B, C, D etc
        myPreciousMap.Add("UCK", categoryA);
        myPreciousMap.Add("SAN", categoryA);
        myPreciousMap.Add("X", categoryX);
    }

    // using it
    public String getCategory(String myString) {
        // this returns exact match (which is recommended)
        // return myPreciousMap.GetValue(myString);

        // this is using the contains
        foreach( KeyValuePair<string, string> kvp in myPreciousMap) {
            if (myString.contains(kvp.getKey()) return kvp.getValue();
        }
        return "Some sort of Default";
    }
}

This way, you avoid all ifs and makes very easy to see correspondent values and edit them.

Answer 4

Although I like Mr Anderson's solution of having an extension method, if you just wanted it done quick and dirty:

        if (new[] { "UCK", "SAN", "AVB", "AVM", "SDS", "DWW", "WQP", "LHG" }.Any(s => myString.Contains(s)))
        {
            mySecondString = "CATEGORY A";
        }

        else if (new[] { "UCT", "SAM", "AHJB", "AVR" }.Any(s => myString.Contains(s)))
        {
            mySecondString = "CATEGORY B";
        }

        else if (new[] { "UKC", "SHZ", "EEB" }.Any(s => myString.Contains(s)))
        {
            mySecondString = "CATEGORY C";
        }

        else
        {
            mySecondString = "CATEGORY D";
        }

Answer 5

Could use a Regular Expression I'm not the best regex maker:

if (Regex.IsMatch(myString, "/(LHG)|(UCK)|(SAN)|(AVB)|(AVM)|(SDS)|(DWW)|(WQP)/")) {
    mySecondString = "CATEGORY A";
} else ...

Here is a good place to test regexes for C#