Segmentation Fault

This is a discussion on Segmentation Fault within the C Programming forums, part of the General Programming Boards category; Hey all, I had previous question that was expertly answered today, and now I have another issue. I am trying ...

  1. #1
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    Question Segmentation Fault

    Hey all,

    I had previous question that was expertly answered today, and now I have another issue. I am trying to display the values I entered into a dynamic 2-dimensional array, but when my code gets to the display loop, I get a segmentation fault. My code so far is below.

    Code:
    #include<stdio.h>
    #include<math.h>
    #include<stdlib.h>
    
    main()  {
            int i, j;
    
            double *CellPtr;
    
            //values to hold row & col size for array & mem size needed
            int col, row, Doubles;
    
            printf("\nEnter the number of columns desired for your array \n");
            scanf("%d", &col);
    
            printf("\nEnter the number of rows desired for your array \n");
            scanf("%d", &row);
    
            Doubles = col * row;
    
            //declaring the array
            double **ArrayPtr;
            ArrayPtr = malloc(row * sizeof(double *));
    
            for(i = 0; i < row; i++)
                    ArrayPtr[i] = malloc(col * sizeof(double));
    
            //filling the array with the requested values
            for(i = 0; i < row; i++)
                    for(j = 0; j < col; j++)        {
                            *ArrayPtr = (int) i * 100 + j;
                            ArrayPtr++;
                    }
    
            //THIS IS GIVING ME THE PROBLEM
            for(i = 0; i < row; i++)
                    for(j = 0; j < col; j++)
                            printf("%d\n", ArrayPtr[i][j]);
    }
    I hope it's OK to include the whole program; it's pretty small.

    If anyone could let me know why I'm getting the segmentation fault (or if there's a glaring, horrific error in my display code logic), I'd really appreciate it.

    Thanks in advance!

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    You moved your ArrayPtr hither and yon throughout the thickets of your doubly-subscripted array. Now: how are you going to get it back?

    (EDIT: And for bonus fun: who says your doubly-subscripted array is all stored in order?)

  3. #3
    and the hat of wrongness Salem's Avatar
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    > printf("%d\n", ArrayPtr[i][j]
    You should have used this notation to write to the array.

    You also need to look up how to use printf as well - %d is not for doubles.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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