Can't Access my 2-D Array in Javascript

Question

this is an array that contains the question on index 0 and choices from 1-4 and then on index 5 contains the answer. I want to access these index numbers individually but cant.

questionbank = [
  ["Which city is the capital of Pakistan", "Islamabad", "Karachi", "Lahore", "Quetta", "Islamabad"],
  ["Which city is the capital of U.A.E", "Dubai", "Abu Dhabi", "Sharjah", "Ras Al-Khaimah", "Dubai"],
  ["Which city is the capital of United States of America", "Austin", "Washington DC", "Boston", "Colorado", "Washington DC"],
  ["Which city is the capital of UK", "London", "Manchester", "Leeds", "Sunderland", "London"],
  ["Which city is the capital of Kuwait", "Kuwait City", "Salmiya", "Jahra", "Tokyo", "Kuwait City"],
  ["Which city is the capital of Saudi Arabia", "Riyadh", "Mecca", "Madinah", "Jeddah", "Riyadh"],
  ["Which city is the capital of India", "Mumbai", "Delhi", "Bareilly", "Calcutta", "Mumbai"],
  ["Which city is the capital of Afghanistan", "Kabul", "Kandahar", "Herat", "Jalalabad", "Kabul"],
  ["Which city is the capital of Ireland", "Dublin", "Belfast", "Cork", "Limerick", "Dublin"]
];

function next_question() {
  text = questionbank[0, 0];
  alert(text);
}

next_question();

The problem is when i call [0,0] the whole sentence in the array comes up instead of just one element in the array. My array is a collection of questions on position 0 and the collection of choices in the other positions. Can you please tell me how to access only one element of the array at a time!

Barmar · Accepted Answer · 2016-04-16 22:06:01Z

1

You're not using the correct syntax to access the second dimension. [0, 0] is equivalent to [0]. The comma doesn't separate dimensions, it's the comma operator that simply evaluates both operands and returns the second one. A multi-dimensional array is an array of arrays, so you access each dimension with a separate set of brackets: arrayname[subscript1][subscript2]

questionbank = [
  ["Which city is the capital of Pakistan", "Islamabad", "Karachi", "Lahore", "Quetta", "Islamabad"],
  ["Which city is the capital of U.A.E", "Dubai", "Abu Dhabi", "Sharjah", "Ras Al-Khaimah", "Dubai"],
  ["Which city is the capital of United States of America", "Austin", "Washington DC", "Boston", "Colorado", "Washington DC"],
  ["Which city is the capital of UK", "London", "Manchester", "Leeds", "Sunderland", "London"],
  ["Which city is the capital of Kuwait", "Kuwait City", "Salmiya", "Jahra", "Tokyo", "Kuwait City"],
  ["Which city is the capital of Saudi Arabia", "Riyadh", "Mecca", "Madinah", "Jeddah", "Riyadh"],
  ["Which city is the capital of India", "Mumbai", "Delhi", "Bareilly", "Calcutta", "Mumbai"],
  ["Which city is the capital of Afghanistan", "Kabul", "Kandahar", "Herat", "Jalalabad", "Kabul"],
  ["Which city is the capital of Ireland", "Dublin", "Belfast", "Cork", "Limerick", "Dublin"]
];

function next_question() {
  text = questionbank[0][0];
  alert(text);
}

next_question();

answered Apr 16, 2016 at 22:06

Barmar

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2 Comments

Muhammad Aurangzeb Khan Over a year ago

Thanks! you're awesome :)

Ivan Yonkov Over a year ago

Nice explanation about the comma operator.

isvforall · Accepted Answer · 2016-04-16 22:06:09Z

0

To access to two-dimensional array you should use this notation [0][0]:

questionbank = [
  ["Which city is the capital of Pakistan", "Islamabad", "Karachi", "Lahore", "Quetta", "Islamabad"],
  ["Which city is the capital of U.A.E", "Dubai", "Abu Dhabi", "Sharjah", "Ras Al-Khaimah", "Dubai"],
  ["Which city is the capital of United States of America", "Austin", "Washington DC", "Boston", "Colorado", "Washington DC"],
  ["Which city is the capital of UK", "London", "Manchester", "Leeds", "Sunderland", "London"],
  ["Which city is the capital of Kuwait", "Kuwait City", "Salmiya", "Jahra", "Tokyo", "Kuwait City"],
  ["Which city is the capital of Saudi Arabia", "Riyadh", "Mecca", "Madinah", "Jeddah", "Riyadh"],
  ["Which city is the capital of India", "Mumbai", "Delhi", "Bareilly", "Calcutta", "Mumbai"],
  ["Which city is the capital of Afghanistan", "Kabul", "Kandahar", "Herat", "Jalalabad", "Kabul"],
  ["Which city is the capital of Ireland", "Dublin", "Belfast", "Cork", "Limerick", "Dublin"]
];

function next_question() {
  text = questionbank[0][0];
  alert(text);
}

next_question();

answered Apr 16, 2016 at 22:06

isvforall

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1 Comment

Muhammad Aurangzeb Khan Over a year ago

Thanks! you're awesome :)

Ivan Yonkov · Accepted Answer · 2016-04-16 22:06:22Z

0

Use the standard notation [dimension][anotherDimension]... in your case [0][0] instead of [0,0]. The last one is not valid in terms of JavaScript or at least does not do what you want. You might have a different background, like C#, where it is a valid multidimensional notation.

answered Apr 16, 2016 at 22:06

Ivan Yonkov

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Comments

Andy · Accepted Answer · 2016-04-16 22:19:00Z

0

This is not questionbank[0, 0] but questionbank[0][0].

edited Apr 16, 2016 at 22:19

Andy

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answered Apr 16, 2016 at 22:06

Jean-Claude Colette

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1 Comment

Muhammad Aurangzeb Khan Over a year ago

Thanks! you're awesome :)

Andy · Accepted Answer · 2016-04-16 22:19:18Z

0

This looks like a 2d array so you should access like:

questionbank[0][0]

edited Apr 16, 2016 at 22:19

Andy

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answered Apr 16, 2016 at 22:07

Richard Guy

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