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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: RE: Re: how to extract numeric part of a string |

Date |
Tue, 17 Dec 2002 12:50:07 -0000 |

Nick Cox > > -charlist- > ========== > > Finally, this utility may be of use or interest: > > =========== begin > program def charlist, rclass > *! NJC 1.0.0 17 Dec 2002 > version 7 > syntax varname(string) [if] [in] > marksample touse, novarlist > * not 0: see [P] file formats .dta > forval i = 1/255 { > capture assert index(`varlist', char(`i')) == > 0 if `touse' > if _rc { > local c = char(`i') > local charlist "`charlist'`c' " > local numlist "`numlist'`i' " > } > } > di as text "`charlist'" > return local charlist "`charlist'" > return local numlist "`numlist'" > end > ========== end > There's a bug in this version of -charlist-, mirroring a longstanding misfeature (bug?) in Stata itself. User-programmers may find a short discussion of interest; others may want, at most, to know that the bug is fixed. In accumulating characters actually met I added them to a list by local c = char(`i') local charlist "`charlist'`c' " Why didn't I go local charlist = "`charlist'" + char(`i') Because this fails on strings longer than the allowed limit in string expressions. However, if char(`i') is char(32), i.e. a space " ", local c = char(32) will _not_ put a space in the local macro -c-. If you don't believe this, try local c = char(32) di "|`c'|" This is a longstanding behaviour of Stata, which strips leading spaces from string expressions. I have been told its historical rationale, which I can't recall at present. Whatever, a work-around is this: if char(`i') == " " { local c " " } else local c = char(`i') local charlist "`charlist'`c' " Note that local c = cond(`i' == 32, " ", char(`i')) would not work for exactly the same reason. I'll post a fixed version of -charlist- to SSC. Nick n.j.cox@durham.ac.uk * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: RE: Re: how to extract numeric part of a string***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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