Thread: Using a Loop and Nested Ifs to Count Number of Vowels in a String

Hey there, I need some advice on how to complete some code. The code needs to take an inputted string from the user, then print out the number of vowels in the string. The challenge here is that I'm only allowed to use nested if statements (so no chained if statements or compound conditions). Here's what I have:

	public static void problem() {
 
		Scanner keyboard = new Scanner(System.in);
		System.out.println("Enter a string and I will tell you the number of vowels that appear.");
		String input = keyboard.nextLine();
		String lowerCaseInput = input.toLowerCase();
		int stringLength = input.length();
		int numberOfOccurancesOfVowels = 0;                                                 
		for (int count = 0; count < stringLength; count++)                     
		{                           
 
		}
			System.out.println("There are " + numberOfOccurancesOfVowels + " vowels in " + input + ".");
 
	}

I don't understand how using nested if statements can complete the task. I know what they are, and how to use them, but I have no idea on how to apply them to this situation. They should be placed within the loop, but what should the conditions be? I was thinking of putting in the following if's within the loop, but it would be both time consuming and extremely long-winded. I'm 100% certain that there is a simpler way.

if ((lowerCaseInput.charAt(count) != 'b'))
{
if ((lowerCaseInput.charAt(count) != 'c'))
{
if ((lowerCaseInput.charAt(count) != 'every other char except for a,e,i,o,u'))
{
numberOfOccurancesOfVowels++;
}
}
}

Thank you for any help you provide. Please don't say anything along the lines of "check out The Java™ Tutorials" or "go buy a Java textbook and read it." I would like some actually helpful information from people who have a better grasp of what to do than I. Again, thanks for reading and any advice.

I'm assuming we can use everything else, but my professor specifically said not to use compound conditions or chained if statements. Yes, we can use other Strings that hold reference data, this is just what I came up with so far.

I think you're talking about the "compareToIgnoreCase" method, but I still don't know how to incorporate it into the nested If statements to get the number of vowels. If I was allowed to use chained If statements or compound conditions then that would be a valid solution.

Originally Posted by Norm

If the assignment's requirements are that a tree of nested if tests be made to determine some condition (a letter is in a group) then my solution bypasses all of that.

Yep this is exactly what the assignment is to do.

Yes, we can do that.

Yes, that should work, but how would I go about doing that?

You're saying to do this:

for (int count = 0; count < stringLength; count++)                     
		{                                                                            
			if (lowerCaseInput.charAt(count) == 'a')                                                                
			{
				numberOfOccurancesOfVowels++;
			}
			else if (lowerCaseInput.charAt(count) == 'e') 
			{
				numberOfOccurancesOfVowels++;
			}
			else if (lowerCaseInput.charAt(count) == 'i') 
			{
				numberOfOccurancesOfVowels++;
			}
			else if (lowerCaseInput.charAt(count) == 'o')
			{
				numberOfOccurancesOfVowels++; 
			} 
			else if (lowerCaseInput.charAt(count) == 'u')
			{
				numberOfOccurancesOfVowels++;
			}
		}

That's the logical way to do it, but that's also using chained if statements as opposed to using nested. I don't know what to do.

Yeah that would serve the same function. Regardless, it wouldn't be using just nested if statements. It's okay. I'll figure it out. Thanks for the help!

Could you not take the inputted String and convert it to a char array? After, you could use a loop that contains nested if statements, where it checks whether each element is a vowel. If so, it increments your counter. The moment a vowel is found, then there's no point in checking the other if-statements, so you can use the keyword, "continue;" (without the " "). It's essentially creating a binary tree in Java. I'm assuming this approach would be allowed since you did not specify whether arrays could be used or not.