Delete root of a binary search tree - c

Question

Im working on a program in C that reads a binary tree from a file and opperates functions on it:insert elements,delete elements,search elements,display elements
With my old debugger it seems that i have 4 warnings and i dont know kow to fix them
Here is the code
#include<stdio.h>
#include<stdlib.h>
#include<stdbool.h>
typedef struct bst
{
double number;
struct bst *leftChild;
struct bst *rightChild;
} node;
node *root = NULL;
void insertNode(double value);
void preOrderPrint(node *root);
node * findMinimum(node *root);
node * deleteNode(node *root, double value);
node* search(node ** tree, double val);
int main()
{
char line[255];
char* endptr;
FILE* f = fopen("tree.txt", "r");
while (fgets(line, sizeof(line), f))
{
if (*line!='*')
{
if(strtod (line, &endptr))
insertNode(strtod (line, &endptr));
else if (strtoimax(line,&endptr,0))
insertNode((strtoimax(line,&endptr,0)));
else
insertNode( strtol (line, &endptr,0));
}
}
fclose(f);
int flag = 0, key;
int choice = 0;
do
{
printf("\nEnter your choice:\n1. Display tree\n2. Insert node\n3. Delete node\n4. Exit\nChoice: ");
scanf("%d", &choice);
switch(choice)
{
case 1:
printf("In Order Display\n");
preOrderPrint(root);
break;
case 2:
printf("Enter key to insert: ");
scanf("%d",&key);
flag = search(&root,key);
if (flag)
{
printf("Key found in tree,cannot insert\n");
}
else
{
printf("Node %d was inserted \n",key);
insertNode(key);
preOrderPrint(root);
}
break;
case 3:
printf("Enter key to delete: ");
scanf("%d", (int*)&key);
flag = search(&root, key);
if (!flag)
{
printf("Key not found in tree,cannot delete\n");
}
else
{
printf("Node %d was deleted \n",key);
deleteNode(root,key);
preOrderPrint(root);
}
break;
case 4:
printf("Memory Cleared\nPROGRAM TERMINATED\n");
break;
default: printf("Not a valid input, try again\n");
}
}
while (choice != 5);
return 0;
}
node * deleteNode(node *currentNode, double value)
{
if(currentNode==NULL) // empty tree
return NULL;
else if(value < currentNode->number) // value is less than node's number. so go to left subtree
currentNode->leftChild = deleteNode(currentNode->leftChild, value);
else if(value > currentNode->number) // value is greater than node's number. so go to right subtree
currentNode->rightChild = deleteNode(currentNode->rightChild, value);
else // node found. Let's delete it!
{
//node has no child
if(currentNode->leftChild == NULL && currentNode->rightChild == NULL)
{
currentNode = NULL;
}
else if(currentNode->leftChild == NULL) // node has only right child
{
currentNode = currentNode->rightChild;
}
else if(currentNode->rightChild == NULL) // node has only left child
{
currentNode = currentNode->leftChild;
}
else // node has two children
{
node *tempNode = findMinimum(currentNode->rightChild);
currentNode->number = tempNode->number;
currentNode->rightChild = deleteNode(currentNode->rightChild, tempNode->number);
}
}
return currentNode;
}
node * findMinimum(node *currentNode)
{
if(currentNode->leftChild==NULL)
return currentNode;
return findMinimum(currentNode->leftChild);
}
void insertNode(double value)
{
node *tempNode;
node *currentNode;
node *parentNode;
tempNode = (node *) malloc(sizeof(node));
tempNode->number = value;
tempNode->leftChild = NULL;
tempNode->rightChild = NULL;
//For the very first call
if(root==NULL)
{
root = tempNode;
}
else
{
currentNode = root;
parentNode = NULL;
while(1)
{
parentNode = currentNode;
if(value <= parentNode->number)
{
currentNode = currentNode->leftChild;
if(currentNode==NULL)
{
parentNode->leftChild = tempNode;
return;
}
}
else
{
currentNode = currentNode->rightChild;
if(currentNode==NULL)
{
parentNode->rightChild = tempNode;
return;
}
}
}
}
}
void preOrderPrint(node *root)
{
if(root==NULL)
return;
preOrderPrint(root->leftChild);
printf("%g ", root->number);
preOrderPrint(root->rightChild);
}
node* search(node ** tree, double val)
{
if(!(*tree))
{
return NULL;
}
if(val < (*tree)->number)
{
search(&((*tree)->leftChild), val);
}
else if(val > (*tree)->number)
{
search(&((*tree)->rightChild), val);
}
else if(val == (*tree)->number)
{
return *tree;
}
//return true;
}
C:\UsersX\Desktop\39\main.c|32|warning: implicit declaration of
function 'strtoimax' [-Wimplicit-function-declaration]|
C:\UsersX\Desktop\39\main.c|56|warning: assignment makes integer from
pointer without a cast [-Wint-conversion]|
C:\UsersX\Desktop\39\main.c|72|warning: assignment makes integer from
pointer without a cast [-Wint-conversion]|
C:\UsersX\Desktop\39\main.c|224|warning: control reaches end of
non-void function [-Wreturn-type]| ||=== Build finished: 0 error(s), 4
warning(s) (0 minute(s), 0 second(s)) ===|
Also the main question would be why i cannot delete the root?
With my debugger it seems that the root can be deleted.