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For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Handling (expanding) tabs in PHP

Question - Is a tab 8 spaces or 4?

Answer - Not quiet either, really. It's a movement of the cursor forward by up to 8 spaces (or 4 spaces or some other number if you have altered your tab stops).

We have many sample programs and data files on our web site (there's a full list, together with all related longer and shorter articles [here]), and they contain something of a mixture of tabs and spaces ... and that (together with the browser's behaviour of compressing multiple white space) leads to some very badly formatted displays unless specific correctional action is taken.

• We display sample source code in a fixed width font, and with <pre> tag, or by specifying pre in the white-space property in CSS (and selecting a fixed width font there too).

• We replace tabs with the appropriate number of spaces in our display scripts - here's the course code to handle a line of text in PHP:
  while (($posn = strpos($line,"\t")) !== false) {
    $spaces = 8 - ($posn % 8) ;
    $line = substr_replace($line,str_repeat(" ",$spaces),$posn,1);
  }





With many file formats, spaces can be interchanged with tabs with little problem, but there are exceptions - the makefile uses the tab character as a delimiter and spaces won't do ... I recall printcap files used to have problems if you used the wrong character, and Python programs that inlcude a mix of tabs and spaces can be very confusing if you rad them with an editor set to none-8 tab spacing. And of course they are vitally important in tab separated value files (.tsv's) of the sort that you'll often use when you export data from a program like Microsoft Excel.
(written 2010-10-29)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
H107 - String Handling in PHP
  [31] Here documents - (2004-08-28)
  [54] PHP and natural sorting - (2004-09-19)
  [337] the array returned by preg_match_all - (2005-06-06)
  [422] PHP Magic Quotes - (2005-08-22)
  [463] Splitting the difference - (2005-10-13)
  [493] Running a Perl script within a PHP page - (2005-11-12)
  [558] Converting between acres and hectares - (2006-01-08)
  [560] The fencepost problem - (2006-01-10)
  [574] PHP - dividing a string up into pieces - (2006-01-23)
  [589] Robust PHP user inputs - (2006-02-03)
  [608] Don't expose your regular expressions - (2006-02-15)
  [642] How similar are two words - (2006-03-11)
  [716] Evaluating arithmetic expressions in configuration files - (2006-05-10)
  [728] Looking ahead and behind in a Regular Expression - (2006-05-22)
  [1008] Date conversion - PHP - (2006-12-26)
  [1058] PHP Regular expression to extrtact link and text - (2007-01-31)
  [1195] Regular Express Primer - (2007-05-20)
  [1336] Ignore case in Regular Expression - (2007-09-08)
  [1372] A taster PHP expression ... - (2007-09-30)
  [1533] Short and sweet and sticky - PHP form input - (2008-02-06)
  [1603] Do not SHOUT and do not whisper - (2008-04-06)
  [1613] Regular expression for 6 digits OR 25 digits - (2008-04-16)
  [1799] Regular Expressions in PHP - (2008-09-16)
  [2046] Finding variations on a surname - (2009-02-17)
  [2165] Making Regular Expressions easy to read and maintain - (2009-05-10)
  [2238] Handling nasty characters - Perl, PHP, Python, Tcl, Lua - (2009-06-14)
  [2629] Curly braces within double quoted strings in PHP - (2010-02-09)
  [3424] Divide 10000 by 17. Do you get 588.235294117647, 588.24 or 588? - Ruby and PHP - (2011-09-08)
  [3515] PHP - moving from ereg to preg for regular expressions - (2011-11-11)
  [3516] Regular Expression modifiers in PHP - summary table - (2011-11-12)
  [3534] Learning to program in PHP - Regular Expression and Associative Array examples - (2011-12-01)
  [3788] Getting more than a yes / no answer from a regular expression pattern match - (2012-06-30)
  [3789] More than just matching with a regular expression in PHP - (2012-06-30)
  [3790] Solution looking for a problem? Lookahead and Lookbehind - (2012-06-30)
  [4071] Setting up strings in PHP - (2013-04-27)
  [4072] Splitting the difference with PHP - (2013-04-27)


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Some other Articles
Testing the new pavement ready for Christmas
Autumn walk from Bowerhill
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Courses for late 2010 and early 2011
Handling (expanding) tabs in PHP
Apache httpd Server Status - monitoring your server
Tuning Apache httpd and Tomcat to work well together
Seventh day traveller on the six day railway
The legal considerations of your web presence - revisited
Logging the performance of the Apache httpd web server
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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