Re: Length of a held expression

*To*: mathgroup at smc.vnet.net*Subject*: [mg96540] Re: [mg96524] Length of a held expression*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Mon, 16 Feb 2009 06:55:18 -0500 (EST)*References*: <200902150823.DAA08017@smc.vnet.net> <E0124336-B0FE-4636-B159-31FB6DC51932@mimuw.edu.pl>

If for some reason you do not like to use Block, here is another pretty simple way: b = Sequence[1, 2]; Length @@ ReplacePart[Hold[{b, 3}], {i_, j_} :> xx] 2 Andrzej Kozlowski On 15 Feb 2009, at 10:44, Andrzej Kozlowski wrote: > I don't know whether this will suit your purpose (because I do not > know what your purpose is) but by far the simplest way to get what > you appear to want is: > > b = Sequence[1, 2]; > > Block[{b}, Length[{b, 3}]] > 2 > > > Andrzej Kozlowski > > > > On 15 Feb 2009, at 09:23, Nikolaus Rath wrote: > >> Hello, >> >> How can I get the length of a list in a Hold[] expression? I.e. if >> >> b = Sequence[1,2]; >> >> then I want the length of {b,3} given as 2. But >> >> Length[{b,3}] >> >> gives me the length after splicing in b (which is 4), while >> >> Length[Hold[{b,3}]] >> >> gives me the length of the hold expression (which is 1). >> >> >> Anyone able to help? >> >> >> Best, >> >> -Nikolaus >> >> -- >> =C2=BBTime flies like an arrow, fruit flies like a Banana.=C2=AB >> >> PGP fingerprint: 5B93 61F8 4EA2 E279 ABF6 02CF A9AD B7F8 AE4E 425C >> >

**References**:**Length of a held expression***From:*Nikolaus Rath <Nikolaus@rath.org>