Thread: simple matrix

Please tell me this is what you meant

Code:

#include<stdio.h>
#include <stdlib.h>


int main (void)
{
  int row_size1,col_size1,row_size2,col_size2;
  int **A;
  int i = 0, j = 0;


  //allocate space for 1 matrix
  // A = malloc(1 * sizeof (int *));




  scanf("%d %d",&row_size1,&col_size1);


  A= malloc(row_size1*sizeof(int*));
  for(i=0;i<row_size1;i++)
    {
      A[i]=(int*)malloc(col_size1*sizeof(int));
    }
  A = malloc(1 * sizeof (int *));




  printf("Enter the elements of the first matrix write 99 when done:");
  for(i=0;i<row_size1;i++)
    {
      for(j=0;j<col_size1;j++)
        {
          scanf("%d",&A[i][j]);
          if (A[i][j] == 99) // 'x' is character variable I declared to \
            break;
        }
    }


  printf("The required matrix is\n");
  for(i=0;i<row_size1;i++)
    {
      for(j=0;j<col_size1;j++)
        printf("%d ",A[i][j]);
      printf("\n");
    }
 for(i=0;i<row_size1;i++)
    {
      free(A[i]);
    }


  free(A);
}

Personally I dont get how you can scanf something before even printing it and.. even if I use the same scanf after printf it only scans 2 values it means it disregards the other values
or maybe thats what you meant

I tried the same program again moving the printf statement to above the scanf but I get a segmentation fault

Your program will do exactly what you write it to do. If you want to tell the user to input a matrix before you read the first values (the size) you have to tell the user before you read the values. The point I was trying to make is that you don't have to print separate prompts to input the size and the values in the matrix.

Post your latest code.

i uncasted my malloc I edited my code so now the memory of A is not lost right?

Code:

#include<stdio.h>
#include <stdlib.h>


int main (void)
{
int row_size1,col_size1,row_size2,col_size2;
int **A;
int i = 0, j = 0;


printf("Enter the elements of the first matrix write 99 when done:");
scanf("%d %d",&row_size1,&col_size1);


A= malloc(row_size1*sizeof(int*));
for(i=0;i<row_size1;i++)
    {
      A[i]=malloc(col_size1*sizeof(int));
    }



A = malloc(1 * sizeof (int *));



for(i=0;i<row_size1;i++)
  {
    for(j=0;j<col_size1;j++)
      {
          scanf("%d",&A[i][j]);
if (A[i][j] == 99) // 'x' is character variable i declared
break;
          }
        }



printf("The required matrix is\n");
for(i=0;i<row_size1;i++)
  {
    for(j=0;j<col_size1;j++)
          printf("%d ",A[i][j]);
          printf("\n");
    }
        for(i=0;i<row_size1;i++)
        {
          free(A[i]);
        }
free(A);
}

My main issue right now is that my program can't seem to understand that the first 2 values the user inputs are the values of the row and column and the rest are the matrix

Originally Posted by zafy

Code:

A = malloc(1 * sizeof (int *));

This line is still suspiciously present in your code.

Wait so you dont want that line at all?
I thought I was supposed to put it after.

Just to be clear this line allocates space for a matrix right? because I might want to add a second matrix later on to this code and I planned on changing the 1 to a 2 since it allocates space for 2 matrices