/* arrDemo1.c
   author: Mark Stehlik
   purpose:
     to demo
       - various forms of declaring arrays
       - passing arrays to functions
       - value and reference parameters
*/

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

#define ARRAY_MAX 5

int getInts(int *a, int *b);
void swapInts(int *a, int *b);
void copyArray(int a[], int aLen, int b[], int bLen);
void swapArrays(int a[], int aLen, int b[], int bLen);
void printArray(int arr[], int arrLen);


int main(int argc, char *argv[])
{
    int a[] = {2,3,5,7,11}; /* these values CAN be changed later on */

    int b[] = { 4,6,8, 12, 16 };

    int c[10], d[7];

    printf("\nBefore array swap swap:\n");
    printf("a = ");
    printArray(a, ARRAY_MAX); /* we pass just the array's name. No []s */
    printf("b = ");
    printArray(b, ARRAY_MAX);

    swapArrays(a, ARRAY_MAX, b, ARRAY_MAX);
    /* Note we don't use & before the array variable names since an array's
       name is the start address of array, the address of the first element */

    printf("\nAfter array swap:\n");
    printf("a = ");
    printArray(a, ARRAY_MAX);
    printf("b = ");
    printArray(b, ARRAY_MAX);

    printf("\nEnter 2 values on line for c[0] and d[0]: ");
    scanf("%d %d", c, d);
    /* it's a good idea to check that scanf returned what you wanted */

  /*if (getInts(c, d) != 0) 
      exit(1);*/
    printf("c[0]: %d\nd[0]: %d\n", c[0], d[0]);

    return 0;
}


/*
  GETINTS: prompts for and returns 2 ints
  return value of 0 means both ints successfully gotten from kbd
  any other value indicates an error.
*/
int getInts(int *a, int *b)
{
    printf("\nEnter two ints sep. by whitespace: ");
    return scanf("%d %d", a, b) - 2;
}

/*
  SWAPINTS: uses addresses/pointers to exchange values of incoming arguments
*/
void swapInts(int *a, int *b)
{
    int temp = *a;
    *a = *b;
    *b = temp;
}

/*
  copyArray: assuming a and b are the same length, copies the corresponding
  values of a into b
*/
void copyArray(int a[], int aLen, int b[], int bLen)
{
    int i;
    if (aLen != bLen)
        return; /* don't try to copy different sized arrays */
    for (i = 0; i < aLen ; i++)
        b[i] = a[i];
}

/*
  swapArrays: assuming a and b are the same length, swaps the corresponding
  values of a and b
*/
void swapArrays(int a[], int aLen, int b[], int bLen)
{
    int i;
    if (aLen != bLen)
        return; /* don't try to swap different sized arrays */
    for (i = 0; i < aLen ; i++)
        swapInts(&a[i], &b[i]); /* RE-USE working code since array elements are int variables */
}

void printArray(int arr[], int arrLen)
{
    int i;
    for (i = 0; i < arrLen; i++)
        printf( "%3d ", arr[i]);
    printf("\n");
}