how to add columns from Matrices(2D array)

ex:

1 2
3 4
------
4 6


I was successful to add the rows but i couldnt figure out how to add the column of this array!

Thank you

Quote:

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Originally Posted by John_shok

ex:

1 2
3 4
------
4 6


I was successful to add the rows but i couldnt figure out how to add the column of this array!

Thank you

---

Can you show us how you added all the rows together? Then we'll show you how to do the column additions. So the result would be:

Code:

---

1 2 | 3
3 4 | 7

---

kind regards,

Jos

int[][] a=new int[2][2];
int m=0;
int sum=0;



for(int j=0;j<a.length;j++){

for(int k=0;k<a[j].length;k++){
m=m+1;
a[j][k]=m;
System.out.print(a[j][k]+ " ");
sum+=m;
}

System.out.print(" >>> "+ sum);
sum=0;
System.out.println();
}

Quote:

---

Originally Posted by John_shok

int[][] a=new int[2][2];
int m=0;
int sum=0;



for(int j=0;j<a.length;j++){

for(int k=0;k<a[j].length;k++){
m=m+1;
a[j][k]=m;
System.out.print(a[j][k]+ " ");
sum+=m;
}

System.out.print(" >>> "+ sum);
sum=0;
System.out.println();
}

---

It's too bad you've done everything at the same time and in the same method. I prefer a couple of separate methods, one that adds all values in a row of a matrix and one that adds all values in a column of a matrix. Here they are:

Code:

---

int addRow(int[][] matrix, int row) {
  int sum= 0;
  for (int col= 0; col < matrix[row].length; col++)
      sum+= matrix[row][col];
  return sum;
}

int addCol(int[][] matrix, int col) {
  int sum= 0;
  for (int row= 0; row < matrix.length; row++)
      sum+=  matrix[row][col];
  return sum;
}

---

As you can see both methods look alike, but one iterates over a single row (the first method) while the other one iterates over a single column (the second method).

kind regards,

Jos

Thank u josh! it is beautiful... I created a new class for addRow and addCol and ran it through driver class.. I was just wondering how one could get this kind of idea.. :D

I thought it worked out good.. but when i tried for 2x3 matrix, it created a problem
created a class for addrow
create a class for colrow
created a drive class

>>AddRow ar=new AddRow();
for(int i=0;i<num.length;i++){
int sumRow = ar.addRow(num, i);
System.out.println("Row"+(i+1)+": "+sumRow);

BUt for colum??
for(int i=0;i<num.length[row];i++){???

i cannot do this?? if i do only num.length[]... this will print out only till 2 columns ,, it is supposed to be 3..

for row it worked out fine..

Josh Thank you again.. I have figure it out ..

Quote:

---

Originally Posted by John_shok

Josh Thank you again.. I have figure it out ..

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Good; I don't know what your problem was because my methods only assume that the matrix isn't 'ragged', i.e. just rectangular or square, and work fine for non-square matrixes.

kind regards,

Jos