2 Dimensional Arrays

Question

How do I use a one dimensional array to store one dimension of a two dimensional array? This is what I have so far, I just can't get the 1D Array to store anything from the 2D array.

Edit: The loop works exactly as it needs to work. I just need to make 2 one dimensional arrays to store each dimension of the 2 dimensional array.

int[][] tutorData = { // students per day (MTW) per tutor {25, 3, 0}, // Amy {14, 5, 12}, // John {33, 22, 10}, // Nick {0, 20, 5}}; // Maria int numOfDays = tutorData[0].length; // number of days = number of "columns" int numOfTutors = tutorData.length; // number of tutors = number of "rows" int[] sumPerDay = {tutorData[i]}; sumPerDay = new int [numOfDays]; // array to store total # of students per day int[] sumPerTutor = {tutorData[j]}; sumPerTutor = new int[numOfTutors]; // array to store total # of students per tutor for (int i = 0; i < tutorData.length; i++) { for (int j = 0; j < tutorData[i].length; j++) { if (j == 0) { System.out.println("Tutor " + (i + 1) + " met: " + tutorData[i][j] + "students on (M) "); } if (j == 1) { System.out.println("Tutor " + (i + 1) + " met: " + tutorData[i][j] + "students on (T) "); } if (j == 2) { System.out.println("Tutor " + (i + 1) + " met: " + tutorData[i][j] + "students on (W) "); } System.out.println(); }

Axel · Accepted Answer · 2013-11-22 16:58:30Z

3

This would be a two-dimensional array because tutorData[i] is an array:

int[] sumPerDay = {tutorData[i]};

Try this:

int[] sumPerDay = tutorData[i];

answered Nov 22, 2013 at 16:58

Axel

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2 Comments

Indyvette Over a year ago

The only thing with this is I have a for loop that prints the 2D array (defining i and j as int(s)), but since the 2 1D arrays are declared before the loop it conflicts, and still prints 0 when I make the adjustments

Axel Over a year ago

Then the problem is that you haven't posted the code containing the for-loops so we can give the advice you need... ;-)

mdolbin · Accepted Answer · 2013-11-22 17:26:55Z

You need to iterate through your 2d array with nested loop and save the sum of values in each of your columns and rows into 2 different arrays.

int[][] tutorData = { // students per day (MTW) per tutor {25, 3, 0}, // Amy {14, 5, 12}, // John {33, 22, 10}, // Nick {0, 20, 5}}; // Maria int numOfDays = tutorData[0].length; // number of days = number of "columns" int numOfTutors = tutorData.length; // number of tutors = number of "rows" int[] sumPerDay = new int [numOfDays]; // array to store total # of students per day int[] sumPerTutor = new int[numOfTutors]; // array to store total # of students per tutor for(int i=0; i<numOfDays; i++){ for(int j=0; j<numOfTutors; j++){ sumPerDay[i] += tutorData[j][i]; sumPerTutor[j] += tutorData[j][i]; } }

sumPerDay will contain sum of values in each column = total number of students for each day.

sumPerTutor will contain sum of values in each row = total number of students for each tutor.

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