sort a set of textlines into alphabetic order.

#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(char *lineptr[], int left, int right);

/* sort input lines */
main(){
    int  nlines;      /* number of input lines read */

    if ((nlines = readlines(lineptr, MAXLINES)) >= 0) {
        qsort(lineptr, 0, nlines -1);
        writelines(lineptr, nlines);
        return 0;
    } else {
          printf("error: input too big to sort\n");
          return 1;
    }
}