Initialize a Variable

[lala]

Hi.
I am trying to assign more than one value to a variable. the variable is "num" and the values are 5 3 7 9 4. I have read the chapter on Declaring & Initializing variables and also Googled it. What am I doing wrong? I just want to run a simple Repetition test. Thank you

	import java.util.*;
	public class RepetitionTest 
{
	 static Scanner console = new Scanner(System.in);
	 public static void main(String[] args)
  {
  	int sum, num;
	
	num = 5,3,7,9,4;
	 sum = 0;
	 num = console.nextInt() ;
	 sum = sum + num ;
	}
}

This is the error message:
RepetitionTest.java:12: ';' expected
num = 5,3,7,9,4;
^
1 error

[Tolls]

"num" is an int, so it can only hold one int.

Are you sure you don't want an int[] (an array)?

[lala]

Thanks for responding Tolls. I've never coded an array. Is this how it should be done?

myA = new int[5]; 
myA = {5 3 7 9 4};
sum = 0;
	 myA = console.nextInt() ;
	 sum = sum + myA ;
	}
}

[JosAH]

Thanks for responding Tolls. I've never coded an array. Is this how it should be done?

myA = new int[5]; 
myA = {5 3 7 9 4};
sum = 0;
	 myA = console.nextInt() ;
	 sum = sum + myA ;
	}
}

Don'y guess; arrays are like a block of houses; an array with five elements is like a block of five houses where the house numbers are 0, 1, 2, 3 and 4. You can store of fetch one value in each house like this:

array[2]= 1;

This sets the value 1 in the house with house number 2. You don't have to use constants for the house numbers; any integer value will do. You can declare and initialize an array like this:

int[] myA = { 5, 3, 7, 9, 4 };

Now all five houses have a value stored in them: 5, 3, ... 4 respectively.

If you want to calculate the sum of all those values you have to do something like this:

int sum= 0; // we haven't added any value yet
for (int i= 0; i < maA.length; i++) // let i be all house numbers in a loop
   sum+= myA[i]; // add the value of house at number i

Study a tutorial on arrays before you start banging your keyboard; it really pays back.

kind regards,

Jos

[Tolls]

You can just do:
int[] myA = {5,3,7,9,4};

However, if all you want to do is add the different elements from the array then why read form the console?

ETA: Oh, beaten to it.

[lonegreyride]

Well I'm very new myself, so maybe I shouldn't answer, but to declare that array, you can do:

int[] num = new int[5];
num = {1,2,3,4,5};

Or simply:
int[] num = {1,2,3,4,5};

Edit: wow, you guys are fast. Two replies in the time it took me to write that. Guess I'll have to get used to the volume of posts on here. :)

[JosAH]

Well I'm very new myself, so maybe I shouldn't answer, but to declare that array, you can do:

int[] num = new int[5];
num = {1,2,3,4,5};

Or simply:
int[] num = {1,2,3,4,5};

Edit: wow, you guys are fast. Two replies in the time it took me to write that. Guess I'll have to get used to the volume of posts on here. :)

Your first example doesn't work; the sequence {1, 2, 3, 4, 5} could have been for a byte or short or long array as well and the compiler can't figure out your intentions, i.e. they are ambiguous.

kind regards,

Jos

[lala]

Whew, this is a lot to digest. Tolls, JosAH, & lonegreyride, I am going to retreat and meditate on all of this information. Be back in a bit.
Thank to all of you,
lala

[lonegreyride]

Your first example doesn't work; the sequence {1, 2, 3, 4, 5} could have been for a byte or short or long array as well and the compiler can't figure out your intentions, i.e. they are ambiguous.

kind regards,

Jos

Ah, thanks. See, I knew I should have held off and let the experts answer. So, to clarify, assigning values to the array with this method ( = {1,2,3,4,5}) should only be done in the same statement that declares the array in the first place? Would this mean that if an array is declared like this (int [] num = new int[5];), then each element has to be assigned a value individually?

[JosAH]

Ah, thanks. See, I knew I should have held off and let the experts answer. So, to clarify, assigning values to the array with this method ( = {1,2,3,4,5}) should only be done in the same statement that declares the array in the first place? Would this mean that if an array is declared like this (int [] num = new int[5];), then each element has to be assigned a value individually?

Yup, that's all correct. The only place you can initialize all the array's values is in its declaration and initialization expression.

kind regards,

Jos

[lonegreyride]

Thanks Jos. That hadn't been made clear to me before now. I apologize to lala if I caused any confusion.

[lala]

Hello again.
I'll start over with my question. I want to see what the values of variables num and sum are for each value: 5 3 7 9 4 (for each iteration of the program). The System.out.print statement only gives me the total of "28" . I apologize for any confusion.

int sum;
	int[] num = {5,3,7,9,4};
	sum = 0;
	for (int i= 0; i < num.length; i++) 
 	sum+= num[i]; 
	System.out.print("i:"  + sum);

[Iron Lion]

You want to make the line that prints the sum part of the for loop, like so:

int sum;
int[] num = {5,3,7,9,4};
sum = 0;
for (int i= 0; i < num.length; i++) {
    sum+= num[i]; 
    System.out.println("i:"  + sum);
}

Not sure why you're starting your output with "i:" though.

[lala]

:o
Ahhhhhhhhhhhhhhhhhhhh... Gee Iron Lion, that just makes so much sense. I wonder why I didn't think of that? <sigh>

Again my deepest gratitude to everyone.
lala