IHYPRESS PROGRAMMING

Tutorials and C programs with code and output for beginners

<09.05>

/* Dynamic allocation of a 2D array */
/* (Software Engineer's Method) */ #include <stdio.h> #include <stdlib.h> /* Dynamic allocation of arrays of more than one dimension is easily done. You can simulate a two-dimensional array with a single, dynamically-allocated one-dimensional array. However, you must now perform subscript calculations manually, accessing the [i][j]th element with array[i * ncolumns + j]. Software engineers prefer this method for its elegance and efficiency */ int main (void) { int nrows, ncols, i, j; int *numbers; /* pointer to the first cell ([0]) */ printf ("How many rows and columns?> "); scanf ("%d%d", &nrows, &ncols); /* allocating the array of integers */ numbers = (int *) calloc (nrows*ncols, sizeof(int)); i=1; j=1; numbers[i*ncols+j] = 9; /* initializes one value to 9 */ for (i=0; i<nrows; i=i+1) { for (j=0; j<ncols; j=j+1) { printf ("%3d ", numbers[i*ncols+j]); } printf ("\n"); } free (numbers); return (0); }

How many rows and columns?> 5 8 0 0 0 0 0 0 0 0 0 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0