How to find first number (0-9) in a string?

[python72]

I need to find first digit (any number 0 - 9) in a string.

I thing I should be able to use:

$NumberPosition = strpos($Source, "/[0-9]/", $NumberPosition+1);

but it does not work, wonder what I am doing wrong?

[kenrbnsn]

You're using the wrong function. strpos does not take a regular expression as an argument.

 

You probably want to look at preg_match or preg_match_all.

 

Ken

[python72]

I need to know position of the digit withing string.

Would preg_match return the position of the digit?

[BlueSkyIS]

<?php

$str = "hello5world";

$parts = str_split($str);

$first_num = -1;
$num_loc = 0;
foreach ($parts AS $a_char) {
if (is_numeric($a_char)) {
	$first_num = $num_loc;
	break;
}
$num_loc++;
}

if ($first_num > -1) {
echo "found number in $str at index $num_loc <br />";
} else {
echo "no numbers found in $str";
}

?>

[Pikachu2000]

If all you need to do is return the position of the first digit in the string, this works. Zero is the position of the first character, but that's easy enough to change. Don't really know if this would more or less efficient than a pattern match, though.

 

<?php
$string = 'This is a string with a 9 number 8.';
$count = strlen($string);
$i = 0;
while( $i < $count ) {
if( ctype_digit($string[$i]) ) {
	echo "First digit found at position $i.";
	return;
}
$i++;
}
?>

 

Returns:

First digit found at position 24.

[BlueSkyIS]

Pikachu2000's is more concise as usual. :-)

[Pikachu2000]

Yours takes into consideration a string that doesn't contain a number at all, though. Mine fails that test.

[kenrbnsn]

If you had read the manual page for preg_match you would know the answer to your question. No it does not, but it does return the matched string, so you can create a function that combines preg_match & strpos. Something like this:

<?php
function digpos($str) {
  $pat = '(\d+)';
  preg_match($pat,$str,$matches);
  return(array($matches[0],strpos($str,$matches[0])));
}
$tests = array('sdfj234skdfl;s','this 1s a test','xxxx');
foreach ($tests as $str) {
   list($matstr,$matpos) = digpos($str);
   if ($matpos !== false) {
      echo "The digits [$matstr] were found at position [$matpos] in the string [$str]<br>\n";
   } else {
      echo "No digits were found in the string [$str]<br>\n";
   }
}
?>

 

Ken