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FT_BITCLR()
Clear (reset) selected bit in a byte
------------------------------------------------------------------------------
Syntax
FT_BITCLR( <cByte>, <nBitPos> ) -> cByte
Arguments
<cByte> is a character from CHR(0) to CHR(255).
<nBitPos> is a number from 0 to 7 conforming to standard
right-to-left bit numbering convention and representing the
position of the bit within the byte.
Returns
Returns new byte, with designated bit cleared (reset).
If parameters are faulty, returns NIL.
Description
In effect, ANDs argument byte with a byte that has all bits set except
the target bit. If bit is already clear (0), it remains clear.
Note: Calls FT_ISBIT() which is also in this Library.
This function is presented to illustrate that bit-wise operations
are possible with Clipper code. For greater speed, write .C or
.ASM versions and use the Clipper Extend system.
Examples
This code would clear bit 4 in a byte represented by CHR(115):
cNewByte := FT_BITCLR( CHR(115), 4 )
? ASC( cNewbyte ) // result: 99
? cNewByte // result: 'c'
This code would clear bit 5 in the byte represented by letter 'A':
FT_BITCLR( 'A', 5 ) // result: 'A', since
// bit 5 already clear
For a demonstration of Clipper bit manipulations, compile and
link the program BITTEST.PRG in the Nanforum Toolkit source code.
Source: BITCLR.PRG
Author: Forest Belt, Computer Diagnostic Services, Inc.
See Also:
FT_BITSET()
FT_ISBIT()
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