Checking if a string contains vowels
You could potentially do:

var vowels = Console.ReadLine()
     .Where(c =&gt; "aeiouAEIOU".Contains(c))
     .Distinct();

foreach(var vowel in vowels)
     Console.WriteLine("Your phrase contains a vowel of {0}", vowel);

if(!vowels.Any())
    Console.WriteLine("No vowels have been detected.");


So you understand the code a bit:


Where() : Will test each character to see if it is indeed a vowel or not.
Distinct() : Will remove duplicate vowels found.


Then you loop through the vowels stating what exist inside, then the if will simply return when loop is empty.