test.c

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

/*
 * Options:
 *     PAREN    - use parenthesis around the ternary
 *     GREATER  - make the root_node's key greater than the key sent to less
 *                (default is less)
 */

/*********************************************************************
 TEST RESULTS:

~/programs/test_this $ g++ -o test test.c
~/programs/test_this $ ./test
node_root->left: 0x0x128e010
node_root->right: 0x0x128e070
node_left: 0x0x128e010
node_right: 0x0x128e030
node_ins: 0x0x128e070
something got set
~/programs/test_this $ g++ -DGREATER -o test test.c
~/programs/test_this $ ./test
node_root->left: 0x0x208c010
node_root->right: 0x0x208c030
node_left: 0x0x208c010
node_right: 0x0x208c030
node_ins: 0x0x208c070
nothing got set
~/programs/test_this $ g++ -DPAREN -o test test.c
~/programs/test_this $ ./test
node_root->left: 0x0x2406010
node_root->right: 0x0x2406070
node_left: 0x0x2406010
node_right: 0x0x2406030
node_ins: 0x0x2406070
something got set
~/programs/test_this $ g++ -DPAREN -DGREATER -o test test.c
~/programs/test_this $ ./test
node_root->left: 0x0xc9c070
node_root->right: 0x0xc9c030
node_left: 0x0xc9c010
node_right: 0x0xc9c030
node_ins: 0x0xc9c070
something got set
~/programs/test_this $ gcc -o test test.c
test.c: In function 'test':
test.c:20:41: error: lvalue required as left operand of assignment
     (p->key > key) ? p->left : p->right = ins;
                                         ^
~/programs/test_this $ gcc -DPAREN -o test test.c
test.c: In function 'test':
test.c:18:43: error: lvalue required as left operand of assignment
     ((p->key > key) ? p->left : p->right) = ins;
                                           ^
 *************************************************************************/

typedef struct node {
    int key;
    struct node *left, *right;
} Node;

void test(Node *p, int key, Node *ins) {
#ifdef PAREN
    ((p->key > key) ? p->left : p->right) = ins;
#else
    (p->key > key) ? p->left : p->right = ins;
#endif
}

int main(int argc, char **argv) {
    Node *node_left = (Node*)calloc(1, sizeof(Node));
    Node *node_right = (Node*)calloc(1, sizeof(Node));
    Node *node_root = (Node*)calloc(1, sizeof(Node));
    Node *node_ins = (Node*)calloc(1, sizeof(Node));

    node_root->left = node_left;
    node_root->right = node_right;

#ifdef GREATER
    test(node_root, -1, node_ins);
#else
    test(node_root, 1, node_ins);
#endif

    printf("node_root->left: 0x%p\n", node_root->left);
    printf("node_root->right: 0x%p\n", node_root->right);
    printf("node_left: 0x%p\n", node_left);
    printf("node_right: 0x%p\n", node_right);
    printf("node_ins: 0x%p\n", node_ins);

    if (node_root->left == node_ins || node_root->right == node_ins)
        printf("something got set\n");
    else
        printf("nothing got set\n");

    free(node_left);
    free(node_right);
    free(node_root);
    free(node_ins);

    return 0;
}