/*
   Phil Ottewell's STL Course - http://www.pottsoft.com/home/stl/stl.htmlx
 
   Example 1.1                  © Phil Ottewell 1997 <philXZY@pottsoftXZY_REMOVEXYZ.com>
  
   Purpose:
            Simple vector and sort demonstration using ANSI C
*/

/* ANSI C Headers */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* Typedef array type in case we need to change it */
typedef int array_type;

/* Function Prototypes */
int compare_values( const void *a, const void *b );
int *get_array_space( int num_items );

int main( int argc, char *argv[] )
{
    int i;
    int nitems = 0;
    array_type ival;
    array_type *v;

    fprintf(stdout,"Enter integers, <Return> after each, <Ctrl>Z to finish:\n");

    while( EOF != fscanf( stdin, "%d", &ival) ) {
      v = get_array_space( nitems+1 );
      v[nitems] = ival;
      fprintf( stdout, "%6d: %d\n", nitems, v[nitems] );
      ++nitems;
    } 

    if ( nitems ) {
      qsort( v, nitems, sizeof(array_type), compare_values );
      for ( i = 0; i < nitems; ++i )
        fprintf( stdout, "%d ", v[i] );
      fprintf( stdout, "\n" );
    }

    return( EXIT_SUCCESS );
}

/*---- Comparison func returns: -ve if a < b,  0 if a == b,  +ve if a > b ----*/
int compare_values( const void *a, const void *b )
{
    const array_type *first, *second;
/*  End of declarations ... */
    first = (array_type *)a;
    second = (array_type *)b;
    return( *first - *second );
}

/*---- Allocate space: n == 0 return pointer, n > 0 expand/realloc if needed -*/
int *get_array_space( int n )
{
    const int extra_space = 2;
    array_type *new_space_ptr;
    static array_type *array_space_ptr;
    static int mxitm;
/*  End of declarations ... */

    if ( n > 0 ) {
      if ( n > mxitm ) {
        n += extra_space;
        if ( array_space_ptr ) {
          new_space_ptr = realloc(array_space_ptr,sizeof(array_type)*n);
          if ( new_space_ptr ) {
/*          Successfully expanded the space */
            array_space_ptr = new_space_ptr;
/*          Clear new storage space */
            memset( &array_space_ptr[mxitm], 0, sizeof(array_type)*(n-mxitm) );
          } else {
/*          Couldn't allocate the space */
            exit( EXIT_FAILURE );
          }
        } else {
          array_space_ptr = (array_type *)calloc( n, sizeof(array_type) );
          if ( !array_space_ptr ) {
/*          Couldn't allocate the space */
            exit( EXIT_FAILURE );
          }
        }    
        mxitm = n;
      }    
    }    
    return( array_space_ptr );
}