How to convert decimal to hex and vice versa?

[pctest]

I know I can use transform("T", "@0") for decimal to hex but I don't find a funtion for hex to decimal.

 

[Mike Gagnon]

pctest

faq184-4461 might help.

Mike Gagnon

If you want to get the best response to a question, please check out FAQ184-2483 first.

 

[pctest]

Mike,

Thank you for the link. Using transform(65535, "@0") will give 0x0000FFFF. ?0xFFFF will give 65535 with width = 5. What are those 0s between x and F for? It seems that they are some sort of placeholder because ?0x00FFFF will give 65535 with width = 8.

 

[craigsboyd]

pctest,

you guessed it pretty much...8 is just the default width.

when you see hex with a default width of 6 it is usually being used as a color. Include the leading 0's (after the 0x of course) or exclude them, they won't effect (or is that affect?) the value of the hex expression.

http://www.sweetpotatosoftware.com

 

[tvign]

Using TRANFORM is cryptic. Better to use functions that are more mathematically friendly. "True Basic" has the answer, and I translated it to a VFP module than can be included in your program with a simple "set procedure to hexlib"

Here it is (copyrighted by 'True Basic'):

* HEXLIB
*
* Version 1.0
* Copyright (c) 1987 by .T. BASIC, Inc.
* All rights reserved.
*
* Bit-manipulation routines
*
* All these routines work properly only for integers.
*
* Conversion functions from numbers to strings:
*
* CONVERT(n,b) converts the integer n to any base b from 2 to 16
* BIN converts n to base 2
* OCT converts n to base 8
* HEX converts n to base 16
* HEXW converts n to 4 base 16 digits, with negative numbers
* treated as two's complement (0 -> "0000", -1 -> "FFFF")
*
* Conversion function from string to number:
*
* CONVERT(s) converts the string s to a number, where s contains
* one of the standard radix marks to indicate the base
* (Unix, Pascal, MS-BASIC, 8086 or 68000 assembler formats
* -- preferred format is a trailing letter H for hex, Q
* for octal, or B for binary)
*
* The conversion functions aren't quite inverses of each other. To
* convert to hexadecimal, you would use HEX. To convert a hex string
* back to a number, if it didn't already have a radix mark (which it
* wouldn't, if it was created by HEX), you'd have to add "H", then
* use CONVERT -- e.g. n = CONVERT(h + "H").
*
*EXTERNAL
*
function convertToHex
parameters number, base
local convert,sign,digit,c,q
sign = ""
digit = 0
c = ""

number = round(number,0)
IF number < 0 then
number = -number
sign = "-"
endif
DO while .T.
do divide with number, base, q, digit
number = q
digit = digit + 1
c = substr("0123456789ABCDEF",digit,1) + c
if number = 0 then
exit && do
endif
enddo
convert = sign + c
return convert
*--------------*
function hex
parameters n
local hex

hex = convertToHex(n,16)
return hex
*--------------*
function oct
parameters n
local oct

oct = convertToHex(n,8)
return oct
*--------------*
function bin
parameters n
local bin

bin = convertToHex(n,2)
return bin
*--------------*
function hexw
parameters n
local hexw,digit,c
digit = 0
c = ""

n = round(n,0)
FOR i = 1 to 4
do divide with n, 16, n, digit
digit = digit + 1
c = substr("0123456789ABCDEF",digit,1) + c
NEXT i
hexw = c
return hexw
*--------------*

* Convert returns the value of the string as a number. The string
* representation may be in binary, octal, decimal, or hexadecimal.
* Hexadecimal is represented by a leading "&H" or "0X", or by a
* leading or trailing "H", "X", or "$". Octal is represented by a
* leading "0" or "&", or by a leading or trailing "O" or "Q". Binary
* is represented by a leading or trailing "B". Any of these may be
* in upper or lower case. If none of these is present, the string is
* assumed to be decimal. If there is a sign ("+" or "-"), it must
* come first.
*
* If an illegal digit for the base is encountered, this routine
* causes an exception (4001, illegal VAL argument).
*
function convert
parameters s
local convert,base,digits,sign,c,i,d,v
*
s = upper(s)
base = 10
sign = 1
*
c = left(s,1)
IF at(c,"-+") > 0 then
IF c = "-" then
sign = -1
endif
s = stuff(s,1,1,"")
c = left(s,1)
endif
*
IF at(c,"0&") > 0 then
s = stuff(s,1,1,"")
base = 8
c = left(s,1)
endif
*
i = 1
d = at(c,"$HXOQ")
IF d = 0 then
i = len(s)
d = at(substr(s,i,1),"$HXOQB")
endif
IF d > 0 then
base = 2*val(substr("888441",d,1))
s = stuff(s,i,1,"")
endif
*
digits = left("0123456789ABCDEF",base)
v = 0
*
FOR i = 1 to len(s)
d = at(substr(s,i,1),digits) - 1
IF d < 0 then
=ask("String "+s+" is not a proper number")
RETURN 0
endif
v = v*base + d
NEXT i
*
convert = sign * v
*
return convert
*--------------*

* Logical functions:
*
* AND(a,b) returns the bitwise logical and of a + b
* OR(a,b) returns the logical or
* XOR(a,b) returns the logical exclusive or
*
function and
parameters a, b
local and
m = 1
b = int(b)
DO while .T.
do divide with a, 2, a, aa
do divide with b, 2, b, bb
r = r + m*aa*bb && multiply is like AND
m = 2*m && m = current bit position
IF b = -1 then
r = r + m*a && if negative, treat as two's complement
exit && do
endif
if b = 0 then && loop until all bits of B are used
exit && do
endif
enddo
and = r
return and
*--------------*
function or
parameters a, b
local or
or = a + b - and(a, b)
return or
*--------------*
function xor
parameters a, b
local xor
xor = a + b - 2*and(a, b)
return xor
*--------------
procedure divide
lparameters x,y,q,r
local sign,sn

if y = 0 then
store 0 to q,r
else
q = int(x/y)
sn = sign(x)*sign
r = sn*mod(abs(x),abs)
endif
endproc
*--------------

 

[rgbean]

How is using all that code less cryptic than Transform()? I expect that using those routines in a situation where a large number of conversions were necessary, would greatly slow up the process. I think these routines are more suited to a FoxBase app - the same generation of software as 'True Basic' - rather than in a VFP app.

Rick