Tutoring web programming, you might encounter a question about Perl. The tutor mentions an observation. Because inline styles use quotes, and then of course printing a string often uses quotes around it, a situation can easily develop in which nested …
Tutoring computer science, extracting a digit is a suggested exercise. The tutor shows a use of Perl’s int() function. Let’s imagine you want to find the hundred-thousands digit of an input number. You can do so with the following code: …
The tutor tells the workings of yesterday’s pattern matching example. In yesterday’s post I mention that the regular expression if ($input=~/item1[^0-9]*[0-9]*.?[0-9]{0,2}/i) can find the pattern item1….$#####.## in a longer string. Here are some explanatory points: =~ is the pattern find …
Perl: regular expressions: yesterday’s code explained Read more »
The tutor demonstrates a Perl regular expression that finds an item name and its price in a string. Suppose you believe that the price of item1 is given in a string, but aren’t sure how exactly it’s said. It could, …
The tutor prepares for a statistics experiment. The first step is to generate two lists: one random, one less so. To generate fifteen random numbers with Perl one can use the following code: for ($i=0;$i
The tutor gives a way to round numbers in Perl. To my knowledge, the best way to round a number in Perl is with its built-in printf() or sprintf(). To round with printf(): Let’s imagine the number is stored in …
The tutor brings up a neat Perl utility that you often see used in discussions between programmers. There are many articles on this site about arrays. To a newcomer, one that might be helpful is here. The point of today’s …
The tutor shows Perl’s way of finding the length of an array. For an intro to arrays, with a Perl example, see my post here. Finding the length of an array is done, in Perl, as follows: $ln=@arra0; print $ln; …
When you tutor computer programming, you must explain the use of variables. Such is the next step of our PERL summer project. To a computer, a value needs a name. Computers (at this level) aren’t capable of changing context the …
Tutoring PERL beginnings, the details can be so important. While the tutor now focuses to the Linux/Mac side, Windows users might do well to tune in. Over my last few posts I’ve been discussing how to get started with PERL …