Fb Memcopyclear

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fb_MemCopyClear

Copies the first bytes of one area into another and sets the rest to zero.

Syntax

Declare Sub fb_MemCopyClear ( ByRef dst As Any, ByVal dstlen As UInteger, ByRef src As Any, ByVal srclen As UInteger )

Parameters

• dst
• dstlen
• src
• srclen

Description

fb_memcopycopy copies a given number of bytes (dstlen) from the memory location src to the memory location dst, but only the first srclen bytes are really copied and the rest is cleared ((dstlen - srclen) bytes).
Each starting address is taken from a reference to a variable or array element.
The memory areas must not overlap (otherwise, the copying is not guaranteed to work properly, especially depending on the platform).
To avoid overflows, the valid memory areas pointed to by both src and dst must be at least equal in size to the number of bytes to be copied (including the bytes cleared).

The underlying type of the objects pointed to by both the source and destination pointers are irrelevant for this function.
The function does not check for any terminating null character in the source area. It always copies exactly the given number of bytes.
The result is a binary copy of the data for the first srclen bytes and a zeroing for the rest ((dstlen - srclen) bytes).

Note: In order to copy from/to memory referenced by a Pointer, it must be dereferenced first (or else specify in argument term the ByVal keyword in front of the pointer name). Otherwise, fb_MemCopyClear will try to copy the bytes from/to the pointer variable's memory location.

Remarks

Usage

fb_memcopy( dst, dstlen, src, srclen )

Differences from QB

• The behavior and usage is new to FreeBASIC.

See also

• Fb_Memcopy
• Fb_Memmove

Examples

Dim src As ZString * 10 = "FreeBASIC"

Dim dst As ZString * 10 = "012345678"

Print "before:"

Print "src = " & src

Print "dst = " & dst

Print

'' copy first 4 bytes and clear the rest

fb_MemCopyClear(dst, SizeOf(dst), src, 4)

Print "after:"

Print "src = " & src

Print "dst = " & dst

Sleep

Output:

before:
src = FreeBASIC
dst = 012345678

after:
src = FreeBASIC
dst = Free

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Category: Memory Functions
Kind: sub

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Reproduced from the FreeBASIC Wiki Manual under the GNU Free Documentation License 1.3 — with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. Copyright © the FreeBASIC project and wiki contributors. See License.