Thread: Extremely basic -- help with multiple arguments

Hello all.

So my first assignment in my computer science class is to write a program that counts the number of vowels. Basically, running

 java main.Assignment1 "This is one argument" "A second one"

should return

Argument 1: 1 a, 2 e, 2 i, 1 o, 1 u
Argument 2: 1 a, 2 e, 0 i, 2 o, 0 u
All: 2 a, 4 e, 2 i, 3 o, 1 u

.

I'm very new Java. I have a working code, but it would only work for one argument:

package main;
public class Assignment1 {
 
	public static void main(String args[]) {
		String str = args[0];
 
		int numA = 0;
		int numE = 0;
		int numI = 0;
		int numO = 0;
		int numU = 0;
 
		for (int i = 0; i < str.length(); i++) {
			char c = str.charAt(i);
			if (c == 'A' || c == 'a') {
				numA++;
			}
			if (c == 'E' || c == 'e') {
				numE++;
			}
			if (c == 'I' || c == 'i') {
				numI++;
			}
			if (c == 'O' || c == 'o') {
				numO++;
			}
			if (c == 'U' || c == 'u') {
				numU++;
			}
		}
		System.out.print("Argument 1: ");
		System.out.print(numA + " a, ");
		System.out.print(numE + " e, ");
		System.out.print(numI + " i, ");
		System.out.print(numO + " o, ");
		System.out.print(numU + " u");
	}
}

My question is how can I make this work for any number of input arguments?

Do what you are currently doing for each element of the args[] array.

Stop and think first. Describe what you will do in real life language before you attempt it in code. Your description will probably begin "For each string in the args[] array...".

Then attempt what you have come up with in code. It depends on what steps you intend taking, but my guess is that your description of the process will involve a second for loop and some more variables.

Originally Posted by newbie

Could follow the approach you've already been following, but enclose all of it in a for loop. You could then do String str = args[indexOfEnclosingLoop];.

I was thinking something like this, but how can the program know to use all of the arguments (be it 2 or 5000)?

Originally Posted by jhnhskll

I was thinking something like this, but how can the program know to use all of the arguments (be it 2 or 5000)?

Arrays have a length property, discussed in the Arrays page of Oracle's Tutorial.

Thanks for the help guys! Here's what I'm working with now:

package main;
 
public class Assignment1 {
 
	public static void main(String args[]) {
		int numA = 0;
		int numE = 0;
		int numI = 0;
		int numO = 0;
		int numU = 0;
 
		for (int idx = 0; idx <= (args.length - 1); idx++) {
			String str = args[idx];
 
			for (int i = 0; i < str.length(); i++) {
				char c = str.charAt(i);
				if (c == 'A' || c == 'a') {
					numA++;
				}
				if (c == 'E' || c == 'e') {
					numE++;
				}
				if (c == 'I' || c == 'i') {
					numI++;
				}
				if (c == 'O' || c == 'o') {
					numO++;
				}
				if (c == 'U' || c == 'u') {
					numU++;
				}
			}
 
			System.out.print("Argument " + (idx + 1) + ": ");
			System.out.print(numA + " a, ");
			System.out.print(numE + " e, ");
			System.out.print(numI + " i, ");
			System.out.print(numO + " o, ");
			System.out.println(numU + " u");
		}
		System.out.print("All: ");
		System.out.print(numA + " a, ");
		System.out.print(numE + " e, ");
		System.out.print(numI + " i, ");
		System.out.print(numO + " o, ");
		System.out.println(numU + " u");
	}
	}
}

This returns

Argument 1: 1 a, 2 e, 2 i, 1 o, 1 u
Argument 2: 2 a, 4 e, 2 i, 3 o, 1 u
All: 2 a, 4 e, 2 i, 3 o, 1 u

when run with the arguments "This is a string" and "Another one"

Now the only issue I'm having is figuring out how to count each separate argument instead of just increasing the count for all of them. I have no idea how to approach this =/

Originally Posted by newbie

Glad you solved it, and thanks for sharing your solution jhnhskll.

Well, I haven't quite gotten it yet. I need some way to count the vowels in each argument separately.

Originally Posted by newbie

Apologies yes, I was away with the fairies when I read your post.
A basic way to accomplish what you need is to use more variables, which you also print, then add to final tally, before resetting the new variables back to 0 at the end of each iteration.

Ohhh I totally get it now. Code working as intended! Thanks for the help!