// Build the heap; note that the size specified during the build is also aligned according to the page size (PageSize), for example, if 15k is specified, 16K will be allocated.
HeapCreate (
  flOptions: DWORD;      {heap attribute options, see table below}
  dwInitialSize: DWORD; {initial size, the unit is byte; the size will be submitted directly to the actual memory}
  dwMaximumSize: DWORD   {Maximum size, set to 0 if the maximum value is not limited}
): THandle;              {return heap handle; 0 is returned for failure, but if exception is allowed by parameter flOptions, exception ID is returned for failure}

// flOptions parameter optional values:
HEAP_NO_SERIALIZE = 1; {Non-mutually exclusive, this flag allows multiple threads to access this heap at the same time}
HEAP_GENERATE_EXCEPTIONS = 4; {When creating a heap error, this flag can raise an exception and return the exception ID}
HEAP_ZERO_MEMORY = 8; {Initialize the allocated memory to 0}

// flOptions parameter may return exceptions when HEAP_GENERATE_EXCEPTIONS is specified:
STATUS_ACCESS_VIOLATION = DWORD ($ C0000005); {Parameter error}
STATUS_NO_MEMORY = DWORD ($ C0000017); {Out of memory}


// Destroy the heap
HeapDestroy (
hHeap: THandle {heap handle}
): BOOL;        {}


// Apply memory from the heap
HeapAlloc (
  hHeap: THandle; {heap handle}
  dwFlags: DWORD; {Memory attribute options, see table below}
  dwBytes: DWORD   {size of application memory, unit is byte}
): Pointer;        {return memory pointer; failure returns 0 or exception, the situation is the same as the establishment of the heap}

// dwFlags parameter optional values:
HEAP_NO_SERIALIZE = 1; {Non-mutually exclusive, this flag allows multiple threads to access this heap at the same time}
HEAP_GENERATE_EXCEPTIONS = 4; {When creating a heap error, this flag can raise an exception and return the exception ID}
HEAP_ZERO_MEMORY = 8; {Initialize the allocated memory to 0}

{It can be seen that this is the same as the heap attribute options; if the dwFlags parameter is set to 0, the heap attributes will be used; if re-specified, the heap attributes will be overwritten}
{Also: if the heap is the default heap, that is, the heap handle is from GetProcessHeap, the dwFlags parameter is ignored}


// Change the size of the heap memory, that is, reallocate
HeapReAlloc (
  hHeap: THandle; {handle}
  dwFlags: DWORD; {Memory attribute option; this parameter has one more option than HeapAlloc, see the table below}
  lpMem: Pointer; {raw memory pointer}
  dwBytes: DWORD   {new size}
): Pointer;        {with HeapAlloc}

// dwFlags parameter optional values:
HEAP_NO_SERIALIZE = 1;   {Non-mutually exclusive, this flag allows multiple threads to access this heap at the same time}
HEAP_GENERATE_EXCEPTIONS = 4;   {When creating a heap error, this flag can raise an exception and return the exception ID}
HEAP_ZERO_MEMORY = 8;   {Initialize the allocated memory to 0}
HEAP_REALLOC_IN_PLACE_ONLY = 16; {This tag does not allow changing the original memory location}


// Get the size of a block of memory in the heap
HeapSize (
  hHeap: THandle; {heap handle}
  dwFlags: DWORD; {memory attribute; optional value is 0 or HEAP_NO_SERIALIZE, the latter ensures synchronous access}
  lpMem: Pointer   {memory pointer}
): DWORD;          {successfully returns the size in bytes; failure returns $ FFFFFFFF}


// Free the specified memory block in the heap
HeapFree (
  hHeap: THandle; {heap handle}
  dwFlags: DWORD; {memory attribute; optional value is 0 or HEAP_NO_SERIALIZE}
  lpMem: Pointer   {memory pointer}
): BOOL;           {}


// verify the heap
HeapValidate (
  hHeap: THandle; {}
  dwFlags: DWORD; {}
  lpMem: Pointer   {}
): BOOL;           {}


// sort the heap
HeapCompact (
  hHeap: THandle; {}
  dwFlags: DWORD   {}
): UINT;           {}


// Lock the heap
HeapLock (
  hHeap: THandle {}
): BOOL;          {}


// Unlock after locking
HeapUnlock (
  hHeap: THandle {}
): BOOL;          {}


// List memory blocks in the heap
HeapWalk (
  hHeap: THandle;                 {}
  var lpEntry: TProcessHeapEntry {}
): BOOL;                          {}

Let’s put an example down.
Orignal link:https://www.cnblogs.com/del/archive/2008/05/08/1188715.html