Aditya Kothadiya’s Blog

I’m working on an interesting project right now, and for this project, I wanted to generate URLs with sequential alphabetic sequence as opposed to using numeric IDs. Using alphabetic string allows me to use short URL addresses with many URL combinations. E.g. If I use numeric indexes, then I can only have 10 possibilities to represent http://abc.com/N, where N= 0 to 9. But instead, if I use alphabetic character, I have 26 possibilities where N= a, b, c to z. I don’t want to add usability issues by using both upper and lower cases of alphabets, so I’ll stick to lower case addresses only.

So I needed a function which will generate sequential alphabetic strings for URL address based on incremental numbers. So I coded up following function:

function getAlphaString($num)
{
  $alpha = '';
  while($num >= 1) {
    $num = $num - 1;
    $alpha = chr(($num % 26)+97) . $alpha;
    $num = $num / 26;
  }
  return $alpha;
}

Use this in a for{} loop, and it will give you sequential strings. Or call with individual numbers as shown below, and it will return you appropriate alphabetic string.

echo getAlphaString(5) . "\n";
echo getAlphaString(500) . "\n";
echo getAlphaString(500000) . "\n";
echo getAlphaString(50000000) . "\n";

And it produced following output:

e
sf
abkpt
dejtlx

Hope you’ll find this function useful in one of your applications.

Splitting strings into an array is nothing new and is pretty easy using the explode function if your input string pattern is consistent. But if your input string pattern is a little less consistent, then using the split function makes it a lot easier than doing some post-processing on array elements produced by the explode function.

Here is an example:

I have an input field where I ask user to enter her friends’ email addresses to invite them. I instruct user to use commas to separate multiple email addresses. But user will not necessarily enter all email addresses with consistent pattern. The input string may not contain any spaces, or may contain optional spaces before or after actual email addresses. For example:

$recipient_email_list = "abc@example.com, def@example.com,ghi@example.com , jkl@example.com , mno@example.com";
$recipient_emails = explode(',', $recipient_email_list);

//Echo with '|' delimiter to see the spaces before and after email address:

foreach ($recipient_emails as $recipient_email)
{
  echo $recipient_email.'|';
}

The output is as below:

abc@example.com| def@example.com|ghi@example.com | jkl@example.com | mno@example.com|

In above example, few exploded strings have additional spaces. So you need to do post-processing on the exploded array as below:

$i=0;
foreach ($recipient_emails as $recipient_email)
{
  $found = preg_match('/ /', $recipient_email);
  if($found)
  {
    $recipient_emails[$i]= trim($recipient_email);
  }
  $i++;
}

foreach ($recipient_emails as $recipient_email)
{
  echo $recipient_email.'|';
}

Then the output is as below:

abc@example.com|def@example.com|ghi@example.com|jkl@example.com|mno@example.com|

But there is another easy way to avoid this extra lines of post-processing code. Use split function as below:

$recipient_emails = split(' *, *', $recipient_email_list);

foreach ($recipient_emails as $recipient_email)
{
  echo $recipient_email.'|';
}

Then the output is as below:

abc@example.com|def@example.com|ghi@example.com|jkl@example.com|mno@example.com|

In above example, split function actually splits an input string into an array by regular expression ‘ *, *’ i.e. split by zero or more spaces after or before the comma character.

I hope you will find this useful. If you have more inputs or questions, then please share in comments section.