quick question

Hey everyone could someone tell me why the first code is working(without functions) and the second one is not?

Code:

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


int main (void)
{
  int row_size1,col_size1,row_size2,col_size2,flag =1;
  int **A;
  int i = 0, j = 0;
  char a,c;


do
  {
    A = malloc(2 * sizeof (int *));

printf("\ncmd> ");
c = getchar();

if(c == 'A')
 {

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

A[0]= malloc(row_size1*sizeof(int*));

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


if(c == 'B')
{
scanf("%d %d",&row_size1,&col_size1);

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

while(flag == 1);
return 0;
}

same code using functions

Code:

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




int main (void)
{
  int row_size1,col_size1,row_size2,col_size2,flag =1;
  int **A=NULL;
  int i = 0, j = 0;
  char a,c;






do
  {
    A = malloc(2 * sizeof (int *));


    printf("\ncmd> ");
    c = getchar();


    if(c == 'A')
      {


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




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




for(i=0;i<row_size1;i++)
    {
      for(j=0;j<col_size1;j++)
        {
          scanf("%d",&A[i][j]);
 }
    }
 matrix_display(A[0], row_size1, col_size1);
      }
 if(c == 'B')
   {


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




     A[1]= malloc(row_size1*sizeof(int*));
     for(i=0;i<row_size1;i++)
       {
         A[i]=malloc(col_size1*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;
           }
       }
     matrix_display(A[1], row_size1, col_size1);
 }
  }
 while(flag == 1);
//return 0;
}


void matrix_display(int *A, int row_size1, int col_size1)
{
  int i,j;
  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);
}

The first one might 'work', but it's still broken none the less.

Code:

$ valgrind ./a.out
==4438== Memcheck, a memory error detector
==4438== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
==4438== Using Valgrind-3.6.1-Debian and LibVEX; rerun with -h for copyright info
==4438== Command: ./a.out
==4438== 

cmd> A 3 2
==4438== Invalid write of size 8
==4438==    at 0x400786: main (bar.c:26)
==4438==  Address 0x51d2050 is 0 bytes after a block of size 16 alloc'd
==4438==    at 0x4C28F9F: malloc (vg_replace_malloc.c:236)
==4438==    by 0x4006FB: main (bar.c:14)
==4438== 
1 2 3
4 5 6
==4438== Invalid read of size 8
==4438==    at 0x4007B4: main (bar.c:31)
==4438==  Address 0x51d2050 is 0 bytes after a block of size 16 alloc'd
==4438==    at 0x4C28F9F: malloc (vg_replace_malloc.c:236)
==4438==    by 0x4006FB: main (bar.c:14)
==4438== 
The required matrix is
1 2 
3 4 
==4438== Invalid read of size 8
==4438==    at 0x40081A: main (bar.c:40)
==4438==  Address 0x51d2050 is 0 bytes after a block of size 16 alloc'd
==4438==    at 0x4C28F9F: malloc (vg_replace_malloc.c:236)
==4438==    by 0x4006FB: main (bar.c:14)
==4438== 
5 6 
==4438== Invalid read of size 8
==4438==    at 0x400878: main (bar.c:45)
==4438==  Address 0x51d2050 is 0 bytes after a block of size 16 alloc'd
==4438==    at 0x4C28F9F: malloc (vg_replace_malloc.c:236)
==4438==    by 0x4006FB: main (bar.c:14)
==4438== 

cmd>

Look at this code.

Code:

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


int main(void)
{
  int row_size1, col_size1, row_size2, col_size2, flag = 1;
  int **A[2];
  int i = 0, j = 0;
  char a, c;


  do {
//    A = malloc(2 * sizeof(int *));

    printf("\ncmd> ");
    c = getchar();

    if (c == 'A') {

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

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

      for (i = 0; i < row_size1; i++) {
        for (j = 0; j < col_size1; j++) {
          scanf("%d", &A[0][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[0][i][j]);
        printf("\n");
      }

      for (i = 0; i < row_size1; i++) {
        free(A[0][i]);
      }
      free(A[0]);
    }
  }

  while (flag == 1);
  return 0;
}

If you want, you can start with
int ***A;
and
A = malloc( 2 * sizeof(int**) );
to replace the array of 2 elements.

Oh I thought the first one was perfect but thanks

but why isn't the second one even compiling? I tried the int ***A

but i honestly thought that this line

Code:

A = malloc( 2 * sizeof(int**) );

just tells the program I am allocating space for 2 matrices A and B

Well if you turned everything into pointers, then you need

void matrix_display(int **A, int row_size1, int col_size1)

is this what you mean?

Code:

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




int main (void)
{
  int row_size1,col_size1,row_size2,col_size2,flag =1;
  int **A=NULL;;
  int i = 0, j = 0;
  char a,c;






do
  {
    A = malloc(2 * sizeof (int **));


    printf("\ncmd> ");
    c = getchar();


    if(c == 'A')
      {


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




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

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


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




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



     for(i=0;i<row_size1;i++)
       {
         for(j=0;j<col_size1;j++)
           {
             scanf("%d",&A[1][i][j]);
             //      if (A[i][j] == 99) // 'x' is character variable i declared
             // break;
           }
       }
     matrix_display(A[1][i][j], row_size1, col_size1);
 }
  }
 while(flag == 1);
}


void matrix_display(int **A, int row_size1, int col_size1)
{
  int i,j;
  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);
}

No, nothing like what I meant.

int ***A;

A is a pointer to a number of matrices
A[0] is a pointer to the first matrix
A[0][0] is a pointer to the first row of the first matrix.


To display one of the matrices, you would do
matrix_display(A[1], row_size1, col_size1);

I suggest you prototype the function before calling it, then you would get some useful diagnostics.
Though TBH, I can't see how this compiles at all without a great deal of complaining from the compiler.

FWIW, matrix_display seems good now, if you can figure out how to call it properly.

Perhaps you should start with
int **A[2];
and get that working properly, before trying to allocate something for int ***A;

please tell me this is what you mean
way too many warnings!

Code:

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


void matrix_display(int *matrix, int row_count, int column_count);




int main (void)
{
  int row_size1,col_size1,row_size2,col_size2,flag =1;
  int **A[2];
  int i = 0, j = 0;
  char a,c;






do
  {
    A = malloc(2 * sizeof (int **));


    printf("\ncmd> ");
    c = getchar();


    if(c == 'A')
      {


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




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




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


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




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




     for(i=0;i<row_size1;i++)
       {
         for(j=0;j<col_size1;j++)
           {
             scanf("%d",&A[1][i][j]);
             //      if (A[i][j] == 99) // 'x' is character variable i declared
             // break;
           }
       }
     matrix_display(A[1], row_size1, col_size1);
 }
  }
 while(flag == 1);
//return 0;
}


void matrix_display(int *A, int row_size1, int col_size1)
{
  int i,j;
  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);
}

> void matrix_display(int *matrix, int row_count, int column_count);
Are you paying even the slightest bit of attention?
In my last post, I said matrix_display was OK, and you go and muck it up again!

Code:

$ gcc -Wall bar.c
bar.c: In function ‘main’:
bar.c:15:8: warning: unused variable ‘a’ [-Wunused-variable]
bar.c:12:37: warning: unused variable ‘col_size2’ [-Wunused-variable]
bar.c:12:27: warning: unused variable ‘row_size2’ [-Wunused-variable]
bar.c:92:1: warning: control reaches end of non-void function [-Wreturn-type]
$ 
$ valgrind ./a.out
==6204== Memcheck, a memory error detector
==6204== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
==6204== Using Valgrind-3.6.1-Debian and LibVEX; rerun with -h for copyright info
==6204== Command: ./a.out
==6204== 

cmd> A
3 2
1 2 3
4 5 6
The required matrix is
1 2 
3 4 
5 6 

cmd> 
cmd> ^C==6204== 
==6204== HEAP SUMMARY:
==6204==     in use at exit: 0 bytes in 0 blocks
==6204==   total heap usage: 4 allocs, 4 frees, 48 bytes allocated
==6204== 
==6204== All heap blocks were freed -- no leaks are possible
==6204== 
==6204== For counts of detected and suppressed errors, rerun with: -v
==6204== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 4 from 4)

TWO changes.
1. fix the prototype of matrix_display
2. remove line A = malloc(2 * sizeof (int **));

So I did what you said I got warnings but... THE program works!
in total I need 4 variables A B C and D so I added for C and D and once again we're back to square 1

Code:

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


void matrix_display(int *matrix, int row_count, int column_count);




int main (void)
{
  int row_size1,col_size1,row_size2,col_size2,flag =1;
  int ****A[4];
  int i = 0, j = 0;
  char a,c;






do
  {
    //  A = malloc(2 * sizeof (int **));


    printf("\ncmd> ");
    c = getchar();


    if(c == 'A')
      {


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




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




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


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




     A[1]= malloc(row_size1*sizeof(int*));
     for(i=0;i<row_size1;i++)
       {
         A[1][i]=malloc(col_size1*sizeof(int));
       }
 for(i=0;i<row_size1;i++)
       {
         for(j=0;j<col_size1;j++)
           {
             scanf("%d",&A[1][i][j]);
             //      if (A[i][j] == 99) // 'x' is character variable i declared
             // break;
           }
       }
     matrix_display(A[1], row_size1, col_size1);




   }


 if(c == 'C')
   {


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




     A[2]= malloc(row_size1*sizeof(int*));
     for(i=0;i<row_size1;i++)
       {
         A[2][i]=malloc(col_size1*sizeof(int));
       }


     for(i=0;i<row_size1;i++)
       {
         for(j=0;j<col_size1;j++)
           {
             scanf("%d",&A[2][i][j]);
             //      if (A[i][j] == 99) // 'x' is character variable i declared
             // break;
           }
       }
     matrix_display(A[2], row_size1, col_size1);
   }


 if(c == 'D')
   {


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




     A[3]= malloc(row_size1*sizeof(int*));
     for(i=0;i<row_size1;i++)
       {
         A[3][i]=malloc(col_size1*sizeof(int));
       }


     for(i=0;i<row_size1;i++)
       {
         for(j=0;j<col_size1;j++)
           {
             scanf("%d",&A[3][i][j]);
             //      if (A[i][j] == 99) // 'x' is character variable i declared
             // break;
           }
       }
     matrix_display(A[3], row_size1, col_size1);
   }




  }
 while(flag == 1);
//return 0;
}

void matrix_display(int ****A, int row_size1, int col_size1)
{
  int i,j;
  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);
}

I made the same changes right?

what thing did i miss again?

Originally Posted by zafy

Code:

void matrix_display(int *matrix, int row_count, int column_count);
void matrix_display(int ****A, int row_size1, int col_size1)

The prototype doesn't match the definition, and now you have... how many stars in there?

Yes! I got it
honestly guys thank you so much I appreciate it so much

I asked you to do it on the last topic you posted - Can you PLEASE fix your indentation

This is my preferred style - Indent style - Wikipedia, the free encyclopedia