This function is used to allocate memory in Windows. It increases the size of a pointer (using realloc()) without damaging its contents. It includes (from what I can tell) all the required error checking for memory allocation    INCLUDE files:
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//**************************************
//     
//INCLUDE files for :Windows Safe alloca
//     te memory
//**************************************
//     
It includes MALLOC.H, STDLIB.H, and WINDOWS.H. It really only needs MALLOC.H, I'm just used to
SDTLIB.H from my early days. WINDOWS.H is used just for the message box function that
outputs error messages.
 
code:
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//     
// Name: Windows Safe allocate memory
// Description:This function is used to 
//     allocate memory in Windows. It increases
//     the size of a pointer (using realloc()) 
//     without damaging its contents. It includ
//     es (from what I can tell) all the requir
//     ed error checking for memory allocation.
//     
// By: Jason Beighel
//
// Inputs:void *WinAddMem(void *Pointer,
//     size_t Amount)
The first parameter is the pointer to be
adjusted, if this parameter does not have any memory allocated to it it must be equal to NULL.
Amount of memory to add to the pointer, usually found with the sizeof() macro, this is only the
memory to add to the pointer not the new size. for instance if the pointer already holding 2
bytes and you want to increase it to 4 bytes then this parameter should be 2, not 4 like it would
be in realloc(). this function determines the amount of memory already assigned to the pointer
and addes this value to it, so you don't need to keep track of that value yourself, incidently
this is why the pointer must equal NULL if it does not have memory assigned to it, from my
experience with it that is the only sure fire method to crash this function.
//
// Returns:It returns the new pointer as
//     type void *, so a typecast is needed to 
//     switch the pointer to the form you are r
//     eally using.
//
// Assumes:Its helpful to have a basic u
//     nderstanding of pointers. Most of the bo
//     okkeeping and error checking for the all
//     ocation process is taken care of for you
//     here (which is the intent) so that can b
//     e ignored.
//
// Side Effects:I don't know of any side
//     effects, but its possibly they exist. Pl
//     ease let me know if you find any. This f
//     unction does not keep track of the memor
//     y and it still must be free() -ed as wit
//     h all other allocated memory.
//
//This code is copyrighted and has// limited warranties.Please see http://
//     www.Planet-Source-Code.com/vb/scripts/Sh
//     owCode.asp?txtCodeId=2134&lngWId=3//for details.//**************************************
//         // Includes ----------------------------
//     ---------------------------------------
#include
#include
#include
// Defines -----------------------------
//     ---------------------------------------
#define WIN_ADDMEM_VERID                "0.01.001"
#define WIN_ADDMEM_ERRPTRLOST        "001"
#define WIN_ADDMEM_ERR_NOADD        "002"
// Structures --------------------------
//     ---------------------------------------
// Classes -----------------------------
//     ---------------------------------------
// Prototypes --------------------------
//     ---------------------------------------
void *WinAddMem(void *Pointer, size_t Amount);
// Globals -----------------------------
//     ---------------------------------------
// Functions ---------------------------
//     ---------------------------------------
void *WinAddMem(void *Pointer, size_t Amount)                {
            size_t OldSize, NewSize;
            if ((Pointer == NULL)&&(Amount == NULL))                            {
                        if (Output != NULL)                                        {
                                    char VerStr[500];
                                    sprintf(VerStr, "Windows Safe Memory Allocation Function\n Ver: %s", WIN_ADDMEM_VERID);
                                    MessageBox(NULL, VerStr, "Version", NULL);
                                    }
                            return NULL;
                            }
                    if (Pointer != NULL)                                    {
                                OldSize = _msize((void *) Pointer);        
                                Pointer = (void *)realloc((void *) Pointer, OldSize + Amount);
                                if (Pointer == NULL)                                                {
                                            if (Output != NULL)                                                            {
                                                        char ErrStr[500];
                                                        sprintf(ErrStr, "\nERROR %s in SafeAddMem()\n Failed to allocate additional memory.", WIN_ADDMEM_ERRPTRLOST);
                                                        MessageBox(NULL, ErrStr, "Error!", NULL);
                                                        }
                                                return NULL;
                                                }
                                        NewSize = _msize((void *) Pointer);
                                        if (OldSize >= NewSize)                                                        {
                                                    if (Output != NULL)                                                                    {
                                                                char ErrStr[500];
                                                                sprintf(ErrStr,"\nERROR %s in SafeAddMem()\n Failed to allocate additional memory.", WIN_ADDMEM_ERR_NOADD);
                                                                MessageBox(NULL, ErrStr, "Error!", NULL);
                                                                }
                                                        return NULL;
                                                        }
                                                }
                                        else                                                        {
                                                    OldSize = 0;
                                                    Pointer = (void *)malloc(Amount);
                                                    if (Pointer == NULL)                                                                    {
                                                                if (Output != NULL)                                                                                {
                                                                            char ErrStr[500];
                                                                            sprintf(ErrStr, "\nERROR %s in SafeAddMem()\n Failed to allocate additional memory.", WIN_ADDMEM_ERRPTRLOST);
                                                                            MessageBox(NULL, ErrStr, "Error!", NULL);
                                                                            }
                                                                    return NULL;
                                                                    }
                                                            
                                                            NewSize = _msize((void *) Pointer);
                                                            if (OldSize >= NewSize)                                                                            {
                                                                        if (Output != NULL)                                                                                        {
                                                                                    char ErrStr[500];
                                                                                    sprintf(ErrStr, "\nERROR %s in SafeAddMem()\n Failed to allocate additional memory.", WIN_ADDMEM_ERR_NOADD);
                                                                                    MessageBox(NULL, ErrStr, "Error!", NULL);
                                                                                    }
                                                                            return NULL;
                                                                            }
                                                                    }
                                                            return Pointer;
                                                            }          

#include
#include
#include
// Defines -----------------------------
//     ---------------------------------------
#define WIN_ADDMEM_VERID                "0.01.001"
#define WIN_ADDMEM_ERRPTRLOST        "001"
#define WIN_ADDMEM_ERR_NOADD        "002"
// Structures --------------------------
//     ---------------------------------------
// Classes -----------------------------
//     ---------------------------------------
// Prototypes --------------------------
//     ---------------------------------------
void *WinAddMem(void *Pointer, size_t Amount);
// Globals -----------------------------
//     ---------------------------------------
// Functions ---------------------------
//     ---------------------------------------
void *WinAddMem(void *Pointer, size_t Amount)
{
  size_t OldSize, NewSize;
  if ((Pointer == NULL)&&(Amount == NULL))
  {
    if (Output != NULL)
    {
      char VerStr[500];
      sprintf(VerStr, "Windows Safe Memory Allocation Function\n Ver: %s", WIN_ADDMEM_VERID);
      MessageBox(NULL, VerStr, "Version", NULL);
    }
    return NULL;
  }
  if (Pointer != NULL)
  {
    OldSize = _msize((void *) Pointer);
    Pointer = (void *)realloc((void *) Pointer, OldSize   Amount);
    if (Pointer == NULL)
    {
      if (Output != NULL)
      {
        char ErrStr[500];
        sprintf(ErrStr, "\nERROR %s in SafeAddMem()\n Failed to allocate additional memory.", WIN_ADDMEM_ERRPTRLOST);
        MessageBox(NULL, ErrStr, "Error!", NULL);
      }
      return NULL;
    }
    NewSize = _msize((void *) Pointer);
    if (OldSize >= NewSize)
    {
      if (Output != NULL)
      {
        char ErrStr[500];
        sprintf(ErrStr,"\nERROR %s in SafeAddMem()\n Failed to allocate additional memory.", WIN_ADDMEM_ERR_NOADD);
        MessageBox(NULL, ErrStr, "Error!", NULL);
      }
      return NULL;
    }
  }
  else
  {
    OldSize = 0;
    Pointer = (void *)malloc(Amount);
    if (Pointer == NULL)
    {
      if (Output != NULL)
      {
        char ErrStr[500];
        sprintf(ErrStr, "\nERROR %s in SafeAddMem()\n Failed to allocate additional memory.", WIN_ADDMEM_ERRPTRLOST);
        MessageBox(NULL, ErrStr, "Error!", NULL);
      }
      return NULL;
    }
    NewSize = _msize((void *) Pointer);
    if (OldSize >= NewSize)
    {
      if (Output != NULL)
      {
        char ErrStr[500];
        sprintf(ErrStr, "\nERROR %s in SafeAddMem()\n Failed to allocate additional memory.", WIN_ADDMEM_ERR_NOADD);
        MessageBox(NULL, ErrStr, "Error!", NULL);
      }
      return NULL;
    }
  }
  return Pointer;
}