#include <stdio.h>
#include <string.h>

#define MAXLINES 5000     /* max #lines to be sorted */
char *lineptr[MAXLINES];  /* pointers to text lines */

int readlines(char *lineptr[], int nlines);
void writelines(char *lineptr[], int nlines);

void qsort(void *lineptr[], int left, int right,
           int (*comp)(void *, void *));
int numcmp(char *, char *);

/* sort input lines */
main(int argc, char *argv[])
{
    int nlines;           /* number of input lines read */
    int numeric = 0;      /* 1 if numeric sort */

    if (argc > 1 && strcmp(argv[1], "-n") == 0)
        numeric = 1;
    if ((nlines = readlines(lineptr, MAXLINES)) >= 0) {
        qsort((void **) lineptr, 0, nlines-1,
          (int (*)(void*,void*))(numeric ? numcmp : strcmp));
        writelines(lineptr, nlines);
        return 0;
    } else {
        printf("input too big to sort\n");
        return 1;
    }
}