# Array with for loop exercise in Nyhoff book

This is an exercise in the Nyhoff book. I am trying to figure out how to output to the consul the column position and the row position 5 times. So that it reads like this:

column: random number, row: random number
column: random number, row: random number
column: random number, row: random number
column: random number, row: random number
column: random number, row: random number

Instead of getting the random number in the array, I am getting the array location. How do I access the individual random numbers?

``````size (150, 200);

int [] columns = new int;
int [] rows = new int;

for (int i = 0; i < columns.length; i++)
{
columns [i] = int (random(0, width));
printArray (columns[i]);
}

for (int j = 0; j < rows.length; j++)
{
rows [j] = int (random(0, height));
printArray (rows[j]);
}

for (int k = 0; k < rows.length; k++)
{
println ("columns: " + columns + "," + "rows: " + rows);
}
``````
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It sounds like it should be a 2D array (grid) and not two 1D array (list) - see tutorials

but as a 1D array Sketch it works like this

• printArray (columns); should be outside the for loops. And it can receive the entire array as a parameter ( `columns`), not only one slot (`columns[i]`)

• In the 3rd for-loop: to address one slot within an array, use: `columns [k]`

Chrisir

``````
size (150, 200);

int [] columns = new int;
int [] rows = new int;

// define columns
for (int i = 0; i < columns.length; i++)
{
columns [i] = int (random(0, width));
}
println("-----------------");
printArray (columns);

// define rows
for (int j = 0; j < rows.length; j++)
{
rows [j] = int (random(0, height));
}
println("-----------------");
printArray (rows);

// ------------------------------------------------------------------

// show content
println("-----------------");
for (int k = 0; k < rows.length; k++)
{
println ("columns: "
+ columns [k]
+ ","
+ "rows: "
+ rows [k]);
}
//
``````

Thank you @Chrisir!!

Yes, at one point I thought to try solving this using 2D array approach. However, because this exercise follows their (the Nyhoffs’) chapter on 1D arrays I wanted to make sure I could do that via 1D as theoretically it’s a simpler structure… (though still it kicked my butt…)  Thank you again!!

1 Like