binary.trees/binary.tree.c
void preorder(Node* root) {
    if (root) {
        printf("%4d", root->data);
        preorder(root->leftChild);
        preorder(root->rightChild);
    }
}
/**
 * preorder: prints the tree with the preorder method (see explaination)
 * @param root the root of the tree
*/
prints the tree with the preorder method
@param root the root of the tree
prints the tree with the preorder method @param root the root of the tree
void preorder(Node* root) {
    if (root) {
        printf("%4d", root->data);
        preorder(root->leftChild);
        preorder(root->rightChild);
    }
}
void preorder ( Node * root ) { if ( root ) { printf ( " " , root -> data ) ; preorder ( root -> leftChild ) ; preorder ( root -> rightChild ) ; } }
preorder: prints the tree with the preorder method (see explaination)
 @param root the root of the tree
preorder : prints the tree with the preorder method ( see explaination ) @param root the root of the tree