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    <p>Here are a couple examples of arrays in familiar situations.</p> <ol> <li><p>You might imagine a 2 dimensional array is as a grid. So naturally it is useful when you're dealing with graphics. You might get a pixel from the screen by saying</p> <pre><code>pixel = screen[20][5] // get the pixel at the 20th row, 5th column </code></pre> <p>That could also be done with a 3 dimensional array to represent 3d space.</p></li> <li><p>An array could act like a spreadsheet. Here the rows are customers, and the columns are name, email, and date of birth.</p> <pre><code>name = customers[0][0] email = customers[0][1] dateofbirth = customers[0][2] </code></pre></li> </ol> <p>Really there is a more fundamental pattern underlying this. Things have things have things... and so on. And in a sense you're right to wonder whether you <em>need</em> multidimensional arrays, because there are other ways to represent that same pattern. It's just there for convenience. You could alternatively</p> <ol> <li><p>Have a single dimensional array and do some math to make it act multidimensional. If you indexed pixels one by one left to right top to bottom you would end up with a million or so elements. Divide by the width of the screen to get the row. The remainder is the column.</p></li> <li><p>Use objects. Instead of using a multidimensional array in example 2 you could have a single dimensional array of Customer objects. Each Customer object would have the attributes name, email and dob.</p></li> </ol> <p>So there's rarely one way to do something. Just choose the most clear way. With arrays you're accessing by number, with objects you're accessing by name.</p>
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    1. POWhy do we use multiple dimensional arrays?
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    1. USTrevor Merrifield
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