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commas in the question

commas in the question

by Bradley Bassinger -
Number of replies: 3
Is there a method to getting a large number in the problem itself to have commas?  I randomly generate about 5 numbers for one problem that are numbers like 10,000,000 or around that number, but I am unsure of how exactly to get those commas in a randomly generated number.  
In reply to Bradley Bassinger

Re: commas in the question

by D. Brian Walton -
Try using regular expressions. I think the following should work, if you create a string from your number using standard formatting. In my first attempt, I did not realize that .pg files have to use a different escape character even in regular expressions.

Here is some sample code that works for the numbers I've tried. Essentially, there is a loop that replaces strings of 4 digits with a comma before the last 3, working from the decimal place to the left. However, it also needs to take into account the possibility of no decimals and needs to avoid putting commas to the right of the decimal place.

$x = 123457890;
$xStr = sprintf("%d", $x);
while ($xStr =~ s/(^[+-]?~~d*)(~~d)(~~d{3})((,~~d{3}|~~.~~d*)*)$/~~1~~2,~~3~~4/) {}

$y = 123456789.123456;
$yStr = sprintf("%f", $y);
while ($yStr =~ s/(^[+-]?~~d*)(~~d)(~~d{3})((,~~d{3}|~~.~~d*)*)$/~~1~~2,~~3~~4/) {}

$z = -123457890.987654321;
$zStr = sprintf("%f", $z);
while ($zStr =~ s/(^[+-]?~~d*)(~~d)(~~d{3})((,~~d{3}|~~.~~d*)*)$/~~1~~2,~~3~~4/) {}

Good luck,

- Brian

D. Brian Walton
James Madison University
In reply to D. Brian Walton

Re: commas in the question

by Dick Lane -
Perhaps this discussion could morph into a wiki-page which describes cosmetics of numbers, numerals, and scientific notation (which is a far-cry from numerology ;-)).

For instance, I might like to display a dollars-and-cents value as $12.70 rather than $12.7 but can accept $12.7 for now while I focus on higher-level stuff to present to my students.  (I do not want "BEST" to be enemy of "GOOD".)

PS: thanks Arnie and Brian for reference and code-fragments.