Method that takes an int array and a value and returns the index of that value in the array-CodePudding

I've spent like an hour trying to figure this one out and I couldn't. This is an exercise for a Java elective course I am taking and I could use some help.

Write a method linearSearch() that takes an array of integers, and an integer value. It should then return the index of the value inside the array (by using a for loop to traverse the elements one by one in order). If the value is not found, -1 should be returned. If more than one value is found, the first occurrence should be returned. Write a program to test your method.

So this is what I tried doing.

public class Exercise6 {
    public static void main(String [] args) {
        int[] a = {3, 6, 70, 3, 7, 9};
        linearSearch(a, 3);
        
    }

    public static void linearSearch(int[] a, int n){  
        int index;      

        for (int i = 0; i < a.length; i  ){
            if (a[i] == n){
                index = i;
                break;
            }
            else {
                index = -1;
            }
        }
        System.out.print(index);
    }
}

But this is obviously wrong. Could you please point me in the right direction? I don't necessarily want you to give me the answer, just give me an idea about the steps.

CodePudding user response：

This will through compilation error as int index; is not initialized. Once initialized, else part would become redundant. Rest would work and deliver you the expected output.

CodePudding user response：

The problem is that you didn't initialize the variable (index):

int index = -1;

but you should think at another way as follows:

1 - read what you want to do

2- You need to make a function that return the index of a specific value of array

3- Define the return type of the function ==> you need to return the index then the function return type is int

4- Define the parameters ==> you have 2 parameters : array and the value

5- You should return the index of value or -1 if it doesn't exist then you will initialize the index = -1

6- Code will be as follows:

public class Exercise6
{
    public static int linearSearch(int[] a, int n){  
        int index = -1;      

        for (int i = 0; i < a.length; i  ){
            if (a[i] == n){
                index = i;
                break;
            }
        }
        return index;
    }

    public static void main(String[] args) {
        int[] a = {3, 6, 70, 3, 7, 9};
        System.out.println(linearSearch(a, 7));
    }
}

Think before Coding

All the best