User defined 2-D array problem

I have to create a program that will have the user define what size the rows and columns are and a starting number. The array will then print out the array starting with the starting number and ending with the ending number, which will be defined as the columns and rows multipled together, plus the starting number. Something like this:

Enter starting value: 50
Enter row size: 5
Enter # of rows: 7
50 51 52 53 54
55 56 57 58 59
60 61 62 63 64
65 66 67 68 69
70 71 72 73 74
75 76 77 78 79
80 81 82 83 84

So far I have:

Code:

---

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


void print2data(int *p, int rows, int cols, int start);

int main(void)
{

        int cols, rows, start;
        int *p;

        printf("Enter starting value: ");
        scanf("%d", &start);
        printf("Enter row size: ");
        scanf("%d", &rows);
        printf("Enter # of rows: ");
        scanf("%d", &cols);


        p = (int*)malloc (rows * cols * sizeof(int));

        print2data(p, rows, cols, start);

        system("PAUSE");
}


void print2data(int *p, int rows, int cols, int start)
{
       
        int i, j, end, last;

        end = (rows * cols) - 1;
        printf("rows*cols = %d\n", end);
        printf("start number is %d\n", start);
        rows = start;
        cols = start;
        last = start + end;

        printf("array is: \n");
        for (i= 0; i <= rows; i++)
        {
                for(j = 0; j <= cols; j++)
                {
                        printf("%d ", *p);
                        p++;
                }
                printf("\n");
        }
}

---

I'm just frustrated with the for statements in the print2data function. I know it's messed up right now, but I keep getting garbage values, and I feel the more I keep writing into the program, the farther I'm getting. Thanks for any help.

Arrays and memory from pointers are indexed starting at 0, which means you should not be reading <= to the rows and columns but rather <.

Another point. You're surprised you're getting garbage values, but you never actually set the values of the elements of the block of memory you allocated. That should be basic knowledge. Memory that you allocate in any form is uninitialized by default, which means it could have any random value. An exception would be calloc() which explicitly sets all of the bits in the memory block to 0.

Im not really surpized I was gettin garbage, I just got frustrated with what I kept getting, so I rewrote the print2data from scratch. I know it's off, but I figured starting fresh would be better.

Code:

---

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


void print2data(int *p, int rows, int cols, int start);

int main(void)
{

        int cols, rows, start;
        int *p;

        printf("Enter starting value: ");
        scanf("&#37;d", &start);
        printf("Enter row size: ");
        scanf("%d", &rows);
        printf("Enter # of rows: ");
        scanf("%d", &cols);


        p = (int*)malloc (rows * cols * sizeof(int));

        print2data(p, rows, cols, start);

        system("PAUSE");
}


void print2data(int *p, int rows, int cols, int start)
{
       
        int i, j, end, last;

        end = (rows * cols);
        rows = end;
        last = start + end;

        printf("rows*cols = %d\n", end);
        printf("start number is %d\n", start);

        printf("array is: \n");
        for (i = start; i < end; ++i)
        {
                printf("%d ", i);
        }
                for(j = start; j < last; ++j)
                {
                        printf("%d ", j);
                }

               
                printf("\n");

}

---

I'm starting to get non garbage numbers that are correct, but they are misplaced. Not sure were to go from here. Any help would be great, thanks.

You didn't read my original reply the way I had intended it. I'll try again.

Code:

---

p = (int*)malloc (rows * cols * sizeof(int));

---

This allocates a block of memory with garbage in it.

Code:

---

print2data(p, rows, cols, start);

---

This prints a block of memory with garbage in it.

Hint: Insert a step where you overwrite the garbage before you print it.

Also, read the FAQ entry on why casting malloc in C is a bad idea.