Modify the given qsort.c program in the following ways:

(1) change low , high , and middle to be pointers to array elements rather than integers representing the array indices. Change the split function to return a pointer, not an integer.

(2) Move the quicksort and split functions in a separate file named quicksort.c . Create a header file named quicksort.h that contains prototypes for the two functions. Include this header file in both qsort.c and quicksort.c .

After your modifications, write a Makefile that compiles the whole program into an executable called qsort . You must create intermediate targets, as shown in class. Do not simply put everything in one target as this is not a good practice, in terms of incremental compilation.

Files that need to be on GitHub: qsort.c -- contains the modified version of the program quicksort.c quicksort.h Makefile to compile the program

Demo: Show that you created quicksort.h as indicated above and that it is included in both qsort.c and quicksort.c (0.5 marks) Show that your Makefile has intermediate targets for this program and run make clean and then make (0.5 marks) Show your modified program that uses pointers (0.5 marks) Run your program so your TA can verify the output (0.5 marks)

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qsort.c:

/* Sorts an array of integers using Quicksort algorithm */ /* Copyright K.N. King -- C programming Ch9.6 */ #include #define N 10 void quicksort(int a[], int low, int high); int split(int a[], int low, int high); int main(void){ int a[N], i; printf("Enter %d numbers to be sorted: ", N); for(i = 0; i < N; i++) scanf("%d", &a[i]); quicksort(a, 0, N - 1); printf("In sorted order: "); for (i = 0; i < N; i++) printf("%d ", a[i]); printf(" "); return 0; } void quicksort(int a[], int low, int high){ int middle; if (low >= high) return; middle = split(a, low, high); quicksort(a, low, middle - 1); quicksort(a, middle + 1, high); } int split(int a[], int low, int high){ int part_element = a[low]; for(;;){ while (low < high && part_element <= a[high]) high--; if(low >= high) break; a[low++] = a[high]; while (low < high && a[low] <= part_element) low++; if (low >= high) break; a[high--] = a[low]; } a[high] = part_element; return high; }