Error 'identifier not found' when using heap function - c++

Question

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
typedef struct{
void** heapAry; //
int last; //
int size; //
int (*compare) (void* argu1, void* argu2); // compare argumentations
int maxSize; //
} HEAP; //stuct HEAP
int compare(void *a, void *b) {
if (a < b)
return -1; // (return minus if former smaller)
if (a > b) // (return plus if former smaller)
return 1;
else
return 0; // (return zero if former smaller)
}
HEAP* heapCreate (int maxSize)
{
HEAP* heap = (HEAP*)malloc(sizeof (HEAP)); //creating heap
if (!heap)
return NULL;
heap->last = -1; // start of last; pre-existing
heap->size = 0; // start of size is zero
// Force heap size to power of 2 -1
heap->maxSize = (int) pow(2, ceil(log((double)maxSize)/log(2.0))) - 1;
heap->heapAry = (void**)calloc(heap->maxSize, sizeof(void*));
return heap;
} // createHeap
bool heapInsert (HEAP* heap, void* dataPtr)
{
if (heap->size >= heap->maxSize) // size cannot be bigger thant maxsize
return false;
++(heap->last); // increment last if insertion is true
++(heap->size); // increment size if insertion is true
heap->heapAry[heap->last] = dataPtr; // The data lies in last of heap
_reheapUp (heap, heap->last); // And arrange the data in order of heap
return true;
}
void _reheapUp (HEAP* heap, int childLoc)
{
int parent = 0;
void** heapAry = NULL;
void* hold = NULL;
if (childLoc){ // if not at root of heap -- index 0
heapAry = heap->heapAry;
parent = (childLoc - 1)/ 2;
if (heap->compare(heapAry[childLoc], heapAry[parent]) > 0) {
// child is greater than parent -- swap
hold = heapAry[parent];
heapAry[parent] = heapAry[childLoc];
heapAry[childLoc] = hold;
_reheapUp (heap, parent);
} // if heap[]
} // if newNode
}
bool heapDelete (HEAP* heap, void** dataOutPtr)
{
if (heap->size == 0) // heap empty
return false;
*dataOutPtr = heap->heapAry[0];
heap->heapAry[0] = heap->heapAry[heap->last];
(heap->last)--;
(heap->size)--;
_reheapDown (heap, 0);
return true;
}
void _reheapDown (HEAP* heap, int root)
{
void* hold = NULL;
void* leftData = NULL;
void* rightData = NULL;
int largeLoc = 0;
int last = 0;
last = heap->last;
if ((root * 2 + 1) <= last){
leftData = heap->heapAry[root * 2 + 1];
if ((root * 2 + 2) <= last) // right subtree
rightData = heap->heapAry[root * 2 + 2];
else
rightData = NULL;
// Determine which child is larger
if ((!rightData) ||
heap->compare (leftData, rightData) > 0){
largeLoc = root * 2 + 1;
} else { // if no right key or leftKey greater
largeLoc = root * 2 + 2;
} // else
// Test if root > larger subtree
if (heap->compare (heap->heapAry[root],
heap->heapAry[largeLoc]) < 0){
// parent < children
hold = heap->heapAry[root];
heap->heapAry[root] = heap->heapAry[largeLoc];
heap->heapAry[largeLoc] = hold;
_reheapDown (heap, largeLoc);
} // if root <
} // if root
} // reheapDown
void* selectK(HEAP *heap, int k){
if(k>heap->size)
return false; // k shouldnt be larger than size
heap->size = heap->last+1;
for(int i=0; i<k; i++){
void * temp = heap-> heapAry[0];
heapDelete(heap, heap->heapAry);
temp = heap->heapAry[heap->last + 1];
}
void * holdout = heap->heapAry[heap->last];
while(heap->last<heap->size){
heap->last++;
_reheapUp(heap, heap->last);
}
return holdout;
}
int main(){
HEAP * heap = heapCreate(256);
heapInsert(heap, (int*)1);
heapInsert(heap, (int*)2);
heapInsert(heap, (int*)3);
heapInsert(heap, (int*)4);
heapInsert(heap, (int*)5);
int *x = (int*) selectK(heap, 3);
printf("%d", *x); //print
}
from above source, I debugged but found two errors '_reheapUp': identifier not found, '_reheapDown': identifier not found. The source code lacks connectivity, as I guess. How may change the heap function? I don't know what to do, this is just on my book, and doesn't make sense