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 Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own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

Posted by pgroves (pgroves), 24 October 2002
If define an array $things with values for $things[1] and $things[2], is $things[0] undefined i.e. are the numner of elements in the array 2 or 3?

cheers

Paul

Posted by admin (Graham Ellis), 25 October 2002
Two. In other words, arrays are sparse and memory is not eaten up allowing for elements that don't (ye) exist.   Here's a sample program, and results, as proof ...

Code:
$ cat phpdemo
#!/usr/bin/php -q

Sample program to show the PHP arrays can be "sparse"


<?php

$thing[3] = 4;
$thing[4] = "more";

$size = count($thing);

print "There are $size elements\n";
?>

We have defined two elements called 3 and 4 in an array,
and our program reports a count of 2 elements

$ ./phpdemo

Sample program to show the PHP arrays can be "sparse"


There are 2 elements

We have defined two elements called 3 and 4 in an array,
and our program reports a count of 2 elements

$




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