Thread: Create a matrix with user-defined dimensions

  1. #1
    Registered User
    Join Date
    Mar 2003
    Posts
    9

    Question Create a matrix with user-defined dimensions

    Well, I am trying to figure out how I can create a matrix with user-defined dimensions. I do need something like that since I am programming some numerical methods that involve matrices. So, I made this code as a test:

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <alloc.h>
    
    void main ()
    {
      int *table=NULL,n,i;
    
      scanf("%d",&n);
      table=(int *) calloc(n,sizeof(n));
      printf ("Input matrix items:\n");
      for (i=0;i<n;i++) {
        scanf("%d",table[i]);
        }
      for (i=0;i<n;i++) {
        printf ("%d,",table[i]);
        }
    }
    Still it does not work and the output I get is: "0,0,...,0,Null pointer assignment." As I am not very familiar with pointers I suppose that is the problem.

  2. #2
    End Of Line Hammer's Avatar
    Join Date
    Apr 2002
    Posts
    6,231
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    
    int main (void)
    {
      int *table,n,i;  
      
      scanf("%d",&n);  
      table=calloc(n,sizeof(n));
      
      printf ("Input matrix items:\n");  
      
      for (i=0;i<n;i++) 
      {
        scanf("%d",&table[i]);    
      }  
      
      for (i=0;i<n;i++) 
      {    
        printf ("%d,",table[i]);
      }
      
      return 0;
    }
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  3. #3
    Registered User
    Join Date
    Mar 2003
    Posts
    9
    How could I extend this code so as to enable the user to define a 2-dimensional NxM matrix?

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