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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 Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own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))
The backtick operator in Python and Perl

In Perl, and in shell programs too, the backtick operator causes the enclosed string to be executed as a command and the result (as generated on STDOUT) returned.

In Python, it's different. The backtick operator causes the enclosed expression to be evaluated and returned as a string.

See string handling resources - Perl
See string handling resources - Python

Example - Python

# This works as the backticks convert the variable twenty to a string ...
twenty = 10 + 10
sentence = "The result is "+`twenty`
print sentence
# ... but this gives a run time error
sentence = "The result is "+twenty
print sentence

Example - Perl

# Reports on the disc utilisation on a Unix of Linux system
$abc = `df`;
print $abc;
(written 2005-05-25, updated 2006-06-05)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
Y108 - Python - String Handling
  [463] Splitting the difference - (2005-10-13)
  [496] Python printf - (2005-11-15)
  [560] The fencepost problem - (2006-01-10)
  [773] Breaking bread - (2006-06-22)
  [903] Pieces of Python - (2006-10-23)
  [943] Matching within multiline strings, and ignoring case in regular expressions - (2006-11-25)
  [954] Splitting Pythons in Bradford - (2006-11-29)
  [970] String duplication - x in Perl, * in Python and Ruby - (2006-12-07)
  [1110] Python - two different splits - (2007-03-15)
  [1195] Regular Express Primer - (2007-05-20)
  [1517] Python - formatting objects - (2008-01-24)
  [1608] Underlining in Perl and Python - the x and * operator in use - (2008-04-12)
  [1876] Python Regular Expressions - (2008-11-08)
  [2284] Strings as collections in Python - (2009-07-12)
  [2406] Pound Sign in Python Program - (2009-09-15)
  [2692] Flexible search and replace in Python - (2010-03-25)
  [2721] Regular Expressions in Python - (2010-04-14)
  [2765] Running operating system commands from your Python program - (2010-05-14)
  [2780] Formatted Printing in Python - (2010-05-25)
  [2814] Python - splitting and joining strings - (2010-06-16)
  [3090] Matching to a string - what if it matches in many possible ways? - (2010-12-17)
  [3218] Matching a license plate or product code - Regular Expressions - (2011-03-28)
  [3349] Formatting output in Python through str.format - (2011-07-07)
  [3468] Python string formatting - the move from % to str.format - (2011-10-08)
  [3469] Teaching dilemma - old tricks and techniques, or recent enhancements? - (2011-10-08)
  [3796] Backquote, backtic, str and repr in Python - conversion object to string - (2012-07-05)
  [3886] Formatting output - why we need to, and first Python example - (2012-10-09)
  [4027] Collections in Python - list tuple dict and string. - (2013-03-04)
  [4152] Why are bus fares so high? - (2013-08-18)
  [4213] Formatting options in Python - (2013-11-16)
  [4307] Identifying and clearing denial of service attacks on your Apache server - (2014-09-27)
  [4360] Python - comparison of old and new string formatters - (2014-12-22)
  [4593] Command line parameter handling in Python via the argparse module - (2015-12-08)
  [4595] Python formatting update - including named completions - (2015-12-10)
  [4659] Prining a pound sign from Python AND running from the command line at the same time - (2016-03-03)

P205 - Perl - Initial String Handling
  [31] Here documents - (2004-08-28)
  [254] x operator in Perl - (2005-03-22)
  [987] Ruby v Perl - interpollating variables - (2006-12-15)
  [1849] String matching in Perl with Regular Expressions - (2008-10-20)
  [1860] Seven new intermediate Perl examples - (2008-10-30)
  [2798] Perl - skip the classics and use regular expressions - (2010-06-08)
  [2816] Intelligent Matching in Perl - (2010-06-18)
  [2832] Are you learning Perl? Some more examples for you! - (2010-06-27)
  [2963] Removing the new line with chop or chomp in Perl - what is the difference? - (2010-09-21)
  [3005] Lots of ways of doing it in Perl - printing out answers - (2010-10-19)
  [3411] Single and double quotes strings in Perl - what is the difference? - (2011-08-30)
  [3547] Using Perl to generate multiple reports from a HUGE file, efficiently - (2011-12-09)
  [3548] Dark mornings, dog update, and Python and Lua courses before Christmas - (2011-12-10)
  [3770] Sample answers to training course exercises - available on our web site - (2012-06-21)


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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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