CLEAR

• Source: https://www.freebasic.net/wiki/wikka.php?wakka=KeyPgClear
• Last revised: 2020-01-17

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Clears or initializes some memory

Syntax

` declare sub Clear cdecl ( byref dst as any, byval value as long = 0, byval bytes as uinteger )

`

Usage

` Clear( dst, [value], bytes )

`

Parameters

dst

starting address of some memory

value

the value to set all bytes equal to

bytes

number of bytes to clear

Description

Clear sets one or more bytes in memory to a certain value (the default value is zero (0) if not specified). The starting address is taken from a reference to a variable or array element.

NOTE: In order to clear memory referenced by a Pointer, it must be dereferenced first (or else specifying in argument term the Byval keyword in front of the pointer name). Otherwise, Clear will try to clear the bytes at the pointer variable's memory location.

Examples

start GeSHi

'create an array with 100 elements
Dim array(0 To 99) As Integer

'clear the contents of the array to 0, starting with the first element
Clear array(0), , 100 * SizeOf(Integer)

'allocate 20 bytes of memory
Dim As Byte Ptr p = Allocate(20)

'set each of the first ten bytes to 0
Clear *p, 0, 10

'set each of the next ten bytes to 42
Clear p[10], 42, 10

'check the values of the allocated bytes
For i As Integer = 0 To 19
    Print i, p[i]
Next

'deallocate memory
Deallocate p

end GeSHi

Differences from QB

• The behavior and usage is new to FreeBASIC
• The keyword CLEAR was used in QB to erase all variables, close all files, and optionally change the stack size. This use is not supported in FreeBASIC.

See also

• Erase
• Reset

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