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qsort

Usage

   include <stdlib.h>
   void qsort(void *base,size_t int nel, size_t size, int
   compar(const void *,const void *));

   ANSI

Description

   qsort is an implementation of the quick-sort algorithm. It sorts a table
   of elements.


   base             Points to the element at the base of the table.


   nel              The number of elements in the table.



   size             The size in bytes of one table element.


   compar           The name of the comparison function, which is called
                    with  two arguments that point to the elements being
                    compared. The function  compar must be written by the
                    programmer and must return an integer that is less than,
                    equal to, or greater than zero according to a comparison
                    of the first argument to the second. compar should be
                    declared as taking  C linkage.


Example 

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

   #define MAXL 10
   unsigned char *line[MAXL];

   #ifdef __cplusplus
   extern "C"
   #endif

   comp( char **a, char **b)
   {
       return strcmp(*a,*b);
   }

   int main()
   {
       int j, k;
       unsigned char buffer[82];
       printf("Enter 10 lines of data\n");
       for(j = 0;j < MAXL; ++j)
           {
               printf("Line: %d\n",j+1);

               if(!fgets((char *)buffer,80,stdin))
                   break;
               line[j] = malloc(strlen((char *)buffer)+1);
               strcpy((char *)line[j],(char *)buffer);
           }

       printf("\n\n\nSort ten lines from stdin:\n");
       qsort(line,j,sizeof(unsigned char *),comp);

       for(k = 0;k < j; ++k)
           printf("Line: %d %s\n",k+1,line[k]);
       return EXIT_SUCCESS;
   }