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Functions.MemAlloc Method

Allocate a static memory buffer of a specified size.

Namespace:  XSharp.RT
Assembly:  XSharp.RT (in XSharp.RT.dll) Version: 2.18
	wBytes AS DWORD
) AS IntPtr
Request Example View Source


Type: DWord
The number of bytes to allocate.

Return Value

Type: IntPtr
A pointer to the allocated space if there is sufficient memory available; otherwise, it returns a NULL_PTR. You should always check the return value for a successful allocation.
MemAlloc() allocates a memory buffer of at least wBytes.
The allocated memory is defined to be static so it is not moved by the garbage collector. Since memory is allocated in increments of 32 bytes, some extra space may be allocated.
For example, a request for even 1 byte will allocate 32 bytes. Space allocated by MemAlloc() is freed by MemFree().
Tip Tip
This function allows the direct manipulation of a memory location and should be used with extreme care.
Tip Tip
The Static Memory Functions (MemAlloc, MemSet etc) are included for compatibility only. In most cases the static memory blocks can (and should) be replaced with arrays of bytes.
Many of the functions in the runtime that take memory blocks as parameter, such as the low level IO functions, now have overloads that take arrays of bytes as parameter.
We recommend that you use these overloads, because their performance is somewhat better.
This example uses MemAlloc() to see whether a specified block is available:
 1FUNCTION IsAvailable(wRequest AS DWORD) AS LOGIC
 2    LOCAL ptrBuff AS PTR
 3    LOCAL lAvailable AS LOGIC
 4    ptrBuff := MemAlloc(wRequest)
 5    IF ptrBuff = NULL_PTR
 6        ? "Memory allocation has failed"
 7        lAvailable := FALSE
 8    ELSE
 9        lAvailable := TRUE
10        MemFree(ptrBuff)
11    ENDIF
12    RETURN lAvailable
See Also