sorting algorithm

I am trying to make a program that takes an array and sorts it. When I try to compile this program, I get a message saying "undefined reference to "_Key"." What am I doing wrong?

sort.h

Code:

---

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define N 100
#define key(A) (A)
#define less(A, B) (Key(A) < key(B))
#define exch(A, B) {int t = A; A = B; B = t;}
#define compexch(A, B) if(less(B, A)) exch(A, B)

void random_array(int a[]);

void sorted_array(int a[]);

void asorted_array(int a[]);

void selection(int a[], int l, int r);

---

sort.c

Code:

---

#include"sort.h"

void random_array(int a[]) {
        int i;
        for(i=0; i<N; i++)
                a[i] = rand();
}

void sorted_array(int a[]) {
        int i;
        for(i=0; i<N; i++)
                a[i] = i+1;
}

void asorted_array(int a[]) {
        int i;
        for(i=0; i<N; i++)
                a[i] = i;
        for(i=0; i<N; i+=10)
                a[i] = rand();
}

void selection(int a[], int l, int r) {
        int i, j;
        for(i = l; i < r; i++) {
                int min = i;
                for(j = i+1; j <= r; j++)
                        if(less(a[j], a[min])) min = j;
                exch(a[i], a[min]);
        }
}

---

sortdriver.c

Code:

---

#include"sort.c"

int main() {
        int a[N], i;


        srand((unsigned) time(NULL));

        random_array(a);
        selection(a, 0, N);
       

        for(i=0;i<10;i++)
                printf("%d ", a[i]);
        printf("\n");

        return 0;
}

---

Code:

---

#define key(A) (A)
#define less(A, B) (Key(A) < key(B))

---

You tell me.

Quzah.

I didn't even notice! Thank you.

Be cautious when using Robert Sedgewick's code. It's a poor translation from Pascal, and a lot of it won't compile directly out of the book.

I am actually having trouble with his quicksort and mergesort algorithm right now. The quicksort won't sort right (and won't even work when I try to sort characters), and the mergesort compiles, but crashes the cmd window I run the program in.