Struct demo: "Trees"

// Program to list trees in nursery catalog according to average height

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

// Constants:

#define MAX_TREES 5 /* maximum number of trees in main program array */
#define MAX_NAME 40 /* 1 + maximum length of a tree's common name */

// Tree description

typedef struct tree_type
{
    int cat_no;                 // catalog number; 1000-1999 for trees
    char variety[MAX_NAME];     // common name of this tree
    int avg_height;             // average height at full growth, in feet
} tree_type;

int main(void)
{
    // First version of program uses fixed data
    tree_type trees[MAX_TREES] = {
        { 1001, "Aspen", 48 },
        { 1002, "Blue Spruce", 64 },
        { 1003, "Dogwood", 21 },
        { 1004, "Ponderosa Pine", 95 },
        { 1005, "Walnut", 80 },
    };

    // List all trees in array:

    printf("Catalog  Expected\n");
    printf("Number   Height     Common Name\n");
    for (int i=0; i<MAX_TREES; ++i)
    {
        printf(" %4d    %3d ft.    %s\n",
               trees[i].cat_no,
               trees[i].avg_height,
               trees[i].variety);
    }

    // Selectively list array entries matching a condition:

    printf("\nTrees under 60 foot height limit:\n");

    int nprinted = 0; // count number of lines printed
    for (int i=0; i<MAX_TREES; ++i)
    {
        if (trees[i].avg_height <= 60)
        {
            ++nprinted; // add to count before printing to use as line #
            printf("%2d. %s (%d)\n",
                   nprinted,
                   trees[i].variety,
                   trees[i].avg_height);
        }
    }

    if (nprinted == 0) // test for no lines printed in loop
        printf(" ***None***\n");

    return 0;
}