adding additional columns to the matrix

Question

I'm allocating memory for a 2d array dynamically using the below code,

int **matrix = (int **) malloc(testVals[m].rows*sizeof(int));
for(int i = 0 ; i < testVals[m].rows ; i++)
    matrix[i] = (int *) malloc(testVals[m].columns*sizeof(int));

but I'm in need to add extra rows and columns as per requirements. I'm able to add extra rows like this, where i'm converting the matrix to square matrix

for(i = rows ; i < cols ; i++)
mat[i] = (int *) malloc(cols*sizeof(int));

but how to do that for adding columns?

those are accessing the structure.. its just the number of rows and columns — Vishal Sharma
– Vishal Sharma, Commented Apr 21, 2014 at 2:15

Community · Accepted Answer · 2017-05-23 12:20:47Z

0

You can use realloc on each row if you need to add a column: That is, if you need to add N columns, you realloc each row by extending each of them by N.

EDIT: You can look at this possible duplicate

edited May 23, 2017 at 12:20

CommunityBot

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answered Apr 21, 2014 at 2:59

quantdev

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2 Comments

Vishal Sharma Over a year ago

the values stored before will sustain?

quantdev Over a year ago

Yes (read my link above on realloc). Values are preserved, only extra memory is allocated. Does that answer your question ?

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