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I am currently working on a program that will roll 5 dice and store a random number for each dice in an array. My problem is my method is only changing the first element and leaving the rest of the elements as 0's. (Only rolling the first dice so to say)

I initialized an array with 5 values, then run this method which takes an array as a parameter, checks if an element is 0, if it is it assigns a random value between 1 and 6.

I've tried doing an enhanced for loop that looks at each element in the array, and theoretically if it is zero, it assigns a random integer between 1 to 6 to it.

public static void rollDice(int[] dice) {

for (int element: dice) {
    int roll = (int)(Math.random()*6) + 1;

    if (element == 0) {
        dice[element] = roll;
    }
}

My results are currently: [Random Number, 0, 0, 0, 0] My expected results are: [5 random integers]

Toastuy
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  • `dice[element]` doesn't make any sense. `element` contains the value, not the index. If you need to modify the value, you'll have to use an old-fashioned for loop. – shmosel Mar 27 '19 at 23:09

4 Answers4

2

This form of the Java for loop loops over the values, not the indexes, of the array. All of the values are 0 and you're using them as the index. You are setting the first element 5 times because of this.

Use a traditional for loop.

for (int index = 0; index < dice.length; index++) {
    // Your roll here

    dice[index] = roll;
}
rgettman
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1

Here

if (element == 0) {
    dice[element] = roll;
}

your code says that if it is the first element, then store the result of the randomization. Since other elements are not the first element, in the case of other elements the condition will be false and consequently the roll will not be stored. Remove this if:

//if (element == 0) {
    dice[element] = roll;
//}
Lajos Arpad
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0
public static void rollDice(int[] dice) {

for (int i=0;i<dice.length;i++) {
    int roll = (int)(Math.random()*6) + 1;

    if (dice[i]== 0) {
        dice[i] = roll;
    }
}

you were changing index 0 5 times because you put the value of array position 0 as the index to change

jonathan Heindl
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0

In dice[element] :

element is NOT the index of the loop, it's the value of the element in the array.

In your case, element is always 0 because java puts 0s in newly created arrays.

You should use an ordinary for loop in this case:

for (int i = 0; i < dice.length; i++) {
        int roll = (int) (Math.random() * 6) + 1;

        if (dice[i] == 0) {
            dice[i] = roll;
        }
}
zin
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