Re: Re: converting hex strings

*To*: mathgroup at smc.vnet.net*Subject*: [mg27464] Re: [mg27434] Re: converting hex strings*From*: maarten.vanderburgt at icos.be*Date*: Tue, 27 Feb 2001 00:37:17 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Bob, Allan, Paul, With the suggestion to use the " " around 16^^, it was not too difficult to convert 32 bit floating point numbers in hexadecimal format to a decimal number, knowing the IEEE format: hexToFloat[x_String] := Module[{str, dig , expo, mant, tt}, str = StringJoin["16^^", x]; dig = IntegerDigits[ToExpression[str], 2]; dig = PadLeft[dig, 32]; expo = FromDigits[dig[[Range[2, 9]]], 2] - 127; tt = Table[1./2^i, {i, 1, 23}]; mant = 1. + Plus @@ (tt*dig[[Range[10, 32]]]); If[dig[[1]] == 0, mant 2^expo, -mant 2^expo] ]; In[72]:= hexToFloat[#]&/@{"42c80000", "bdfcd35b","3dfcd35b", "bf800000"} Out[72]= {100., -0.12345, 0.12345, -1.} Thanks a lot for your help Maarten "Paul Lutus" <nospam at nosite.com> on 26-02-2001 02:55:37 AM cc: Subject: [mg27464] [mg27434] Re: converting hex strings <maarten.vanderburgt at icos.be> wrote in message news:97a7b2$aks at smc.vnet.net... > Hallo, > > I have a list of hexadecimal strings (read from a hex string text file): > e.g. {"01a0", "fffe", "0080"} representing integers. > How can I convert such a list to integers so that I get {416, 4094, 128}? > I cannot make a function using something like > > hextoint = 16^^#& > > or > > hextoin = 16^^ToExpression[#]& > > I get errors like below: > > In[44]:= hexstr = "a1b0" > t = ToExpression[hexstr]; > 16^^t > General::"digit": "Digit at position \!\(1\) in \!\(\"t\"\) is too large to > \ > be used in base \!\(16\)." > > Where does this error come from? > > While this works ok: > In[43]:= 16^^a1b0 > Out[43]= 41392 > > The ToExpression[ ] also would give problems: ToExpression["01a0"] returns > 0. > > Has anyone done anything along these lines? I think this will do it for you: myhex[x_String] := Module[ {str}, str = StringJoin["16^^",x]; ToExpression[str] ]; data = {"01a0","fffe","0080"}; Map[myhex,data] {416,65534,128} > How would I have to convert a hex list representing floats (IEEE floating > point standard)?, e.g. {"42c8000", "3dfcd35b", "bf80000"} which should > convert to {100.0, 0.12345, -1.0} in a decimal notation. I think that will be much more difficult -- it will require a full grasp of the IEEE specification within the converter code. -- Paul Lutus www.arachnoid.com