Re: A simple swap function

• To: mathgroup at smc.vnet.net
• Subject: [mg2165] Re: A simple swap function
• From: ianc (Ian Collier)
• Date: Wed, 11 Oct 1995 01:58:41 -0400
• Organization: Wolfram Research, Inc.

```In article <44qj8g\$s22 at ralph.vnet.net>, valentin at wam.umd.edu (William F.
Campbell) wrote:

>   I think I must be missing something straightforward.  I want a function
> to swap the values of 2 lists.  I defined ab={a,b}, and ba={b,a}, and
> swap[v1_,v2_]:=Module[{temp=v1},v1=v2;v2=temp;], and I get an Iteration
> limit exceeded error.  When I look at ab, it looks like {Hold[a],Hold[b]}
> (or maybe {Hold[b],Hold[a], I don't remember), and ba looks opposite.  When
> I tried to use the same function on numbers, it didn't work either.  What's
> wrong with what I'm doing, and how can I do what I want to do?

Well, in this example you can simply use the Reverse function to
swap your values:

In[9]:=
ab = {a,b}
Out[9]=
{a, b}
In[10]:=
ba = Reverse[ ab ]
Out[10]=
{b, a}

I hope this helps.

--Ian

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Ian Collier
Technical Sales Support
Wolfram Research, Inc.
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tel:(217)-398-0700     fax:(217)-398-0747      ianc at wri.com
Wolfram Research Home Page:             http://www.wri.com/
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```

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