PHP: Best way to split string into alphabetic and numeric components

Question

I have several strings of the format

AA11
AAAAAA1111111
AA1111111

Which is the best (most efficient) way to sepa

Answer 1

This seems to work but when you try to pass something like "111111", it doesn't.

In my application, I am expecting several scenarios and what seems to be doing the trick is this

$referenceNumber = "AAA12132";
$splited = preg_split('/(\d+)/', $referenceNumber, -1, PREG_SPLIT_DELIM_CAPTURE);
var_dump($splited);

Note:

1. Getting an array of 2 elements, it means the 0th index is the alpha while the 1st is the numerics.
2. Getting array of just 1 element, means the 0th element is the numeric and no alphas.
3. If you get more than 2 array items, then your string must be in this format “AAA1323SDC”

So given the above, you can play around with it based on your use case.

Cheers!

Answer 2

Here is a working example using preg_split():

$strs = array( 'AA11', 'AAAAAA1111111', 'AA1111111');

foreach( $strs as $str) 
    foreach( preg_split( '/([A-Za-z]+)/', $str, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY) as $temp)
        var_dump( $temp);

This outputs:

string(2) "AA"
string(2) "11"
string(6) "AAAAAA"
string(7) "1111111"
string(2) "AA"
string(7) "1111111"

Answer 3

Instead of using RegEx straight away you can add one extra check for example:

if (ctype_alpha($testcase)) {
   // Return the value it's only letters
} else if(ctype_digit($testcase)) {
   // Return the value it's only numbers
} else {
   //RegEx your string to split nums and alphas
}

EDIT: Obviously my answer didn't give an evidence which will perform better, that's why I did a test that produced the following result:

1. preg_split took 5.3319189548492 seconds
2. sscanf took 3.4432129859924 seconds

And the answer should have been sscanf

Here's the code that produced the result:

$string = "AAAAAAAAAA111111111111111";
$count = 1000000;

function prSplit($string) {
    return preg_split( '/([A-Za-z]+)/', $string, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
}

function sScanfTest($string) {
    return sscanf($string, "%[A-Z]%[0-9]");
}

function microtime_float()
{
    list($usec, $sec) = explode(" ", microtime());
    return ((float)$usec + (float)$sec);
}

$startTime1 = microtime_float();
for($i=0; $i<$count; ++$i) {
    prSplit($string);
}
$time1 = microtime_float() - $startTime1;
echo '1. preg_split took '.$time1.' seconds<br />';

$startTime2 = microtime_float();
for($i=0; $i<$count; ++$i) {
    sScanfTest($string);
}
$time2 = microtime_float() - $startTime2;
echo '2. sscanf took '.$time2.' seconds';

Answer 4

If they're all a series of alpha, followed by a series of numeric, with no non-alphameric characters, then sscanf() is probably more efficient than regexp

$example = 'AAA11111';
list($alpha,$numeric) = sscanf($example, "%[A-Z]%d");

var_dump($alpha);
var_dump($numeric);

Answer 5

preg_split should do the job fine.

preg_split('/(\w+)/', $input, -1, PREG_SPLIT_DELIM_CAPTURE);

The preg library is surprisingly efficient in handling strings, so I would assume it to be more efficient than anything you can write by hand, using more primitive string functions. But do a test and see for your self.