Re: List manipulation question

*To*: mathgroup at smc.vnet.net*Subject*: [mg15898] Re: [mg15852] List manipulation question*From*: BobHanlon at aol.com*Date*: Wed, 17 Feb 1999 23:33:43 -0500*Sender*: owner-wri-mathgroup at wolfram.com

In a message dated 2/12/99 8:48:03 PM, Maarten.vanderBurgt at icos.be writes: >In the following piece of code I define a function Swap23 which is ment >to swap elements 2 and 3 in a list. >Executing the function on a simple list I get an error. Why do I get >this error? Why do I not get this error when I execute the commnad from >Swap23 "by hand" as is shown in In[4]? > Maarten, Use the following: Swap23[L_List]:=Module [ {a = L, temp}, temp = a[[2]]; a[[2]]=a[[3]]; a[[3]] =temp; a ]/; Length[L] > 2 myList = {1,2, 3}; Swap23[myList] {1,3,2} Bob hanlon