How to get part of array elements by user input using a loop

If you have a Java array as follows:

double myarr[10];

You access elements in an array by index (assuming the array has been populated with data)

double somenum = myarr[3]; // extracts the *fourth* element from the list

To set a value in the array, you use the assignment operator and specify a value:

myarr[7] = 3.14159; // sets the *eighth* element to value '3.14159'

If you wish to iterate over a range of numbers, you can use a for-loop. For-loops have the following format:

for (initialization; condition; increase)

If you wanted to print all numbers between 1 and 10, you can write:

for (int i=1; i<=10; i++) {
    System.out.println(i);
}

The trick is to use the variable i in the for-loop and ensure the loop iterates over the proper range. Hint: You can use i as an array index.

Here are some good resources:

• Java: Array with loop
• http://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html
• http://www.tutorialspoint.com/java/java_loop_control.htm
• http://www.homeandlearn.co.uk/java/java_for_loops.html

Here's a loop and a means for user input:

Scanner reader = new Scanner(System.in);

for(int i=2; i<8; i++){
    System.out.println("Enter Element "+i);
    a=reader.nextInt();
    //store "a" somewhere
}

c needs to start at 1 (since you want the second elment) and stop at 8 (for the ninth) so for(int c=1;c<9;c++) should be the loop

When writing loops remember;

• array indexes are 0 based, the first element is at 0, the second at 1 up to the last which is at the length of the array minus 1
• if your loop increments, then the smallest value it can have is what ever it starts as, so you shouldn't check to make sure its greater then that, (ie if you start at 2 and increment then you don't need to check to if its greater than or equal to 2 because it always is)

Take a look at the syntax for for loops here

Console console = System.console();
double arr[10];
for(int c = 1; c<10; c++){ 
    String input = console.readLine("Enter a value for the elements 2-9: ");
    arr[c] = Double.parseDouble(input);
    System.out.println(arr[c]);
}