Finding a string from the string collection

As Uncle Ben once said, "With great power comes great responsibility"

The same is true with the Contains feature; we need it in a variety of situations to accomplish a variety of tasks, but we often run into problems. To better understand this, let's look at an example.

            var myString = "AmIThere";
            var container = "AmIThereIsThere";
            var container1 = "AmIthereIsThere";

            if(container.Contains(myString))
                Console.WriteLine("My String is available in container");
            else
                Console.WriteLine("My String is not available in container");

            if (container1.Contains(myString))
                Console.WriteLine("My String is available in container1");
            else
                Console.WriteLine("My String is not available in container1");

            /*
             Output:
                My String is available in container
                My String is not available in container1
             */

Now one question might come, in both cases, we were comparing the same string but how come it failed in the second check, the reason is

Contains method is Case-sensitive

In the real world, we might face a situation wherein we need to check if a string contains our expected string and not know the case of an incoming string.

What's the alternative we have?

Below are the options we can use to solve our case-sensitive issue from Contains method

// Option1: Using Regex
            if (Regex.IsMatch(container1, Regex.Escape(myString), RegexOptions.IgnoreCase))
                Console.WriteLine("My String is available in container1");
            else
                Console.WriteLine("My String is not available in container1");

            // Option2: Using IndexOf
            if (container1.IndexOf(myString, StringComparison.OrdinalIgnoreCase) != -1) //If string matches then IndexOf would return index of first occurence else -1
                Console.WriteLine("My String is available in container1");
            else
                Console.WriteLine("My String is not available in container1");

//Option3: Using the overloaded Contains method, available only with newer versions of .Net
            if (container1.Contains(myString, StringComparison.CurrentCultureIgnoreCase))
                Console.WriteLine("My String is available in container");
            else
                Console.WriteLine("My String is not available in container");

Hope you found this post useful :)