Search For Characters in a String - php

Question

$str1 = "HEADINGLEY";
$str2 = "HDNGLY";
how can i seach string 1 to see if it contains all the characters from string 2 in the order they exist in string 2 and return a true or false value ?
Any help appreciated :D
if this helps, this is the code i have todate..
echo preg_match('/.*H.*D.*N.*G.*L.*Y.*/', $str1, $matches);
returns 0

Answer 1

I guess I'd use preg_match
http://us.php.net/manual/en/function.preg-match.php
...and turning $str2 into a regular expression using str_split to get an array and implode to turn it back into a string with ".*" as glue between characters.
http://us.php.net/manual/en/function.str-split.php
http://us.php.net/manual/en/function.implode.php
Upate -- I should have suggested str_split instead of explode, and here is the code that will get you a regular expression from $str2
$str2pat = "/.*" . implode(".*", str_split($str2)) . ".*/";

Answer 2

You could use some regular expression match like .*H.*D.*N.*G.*L.*Y.* and preg_match.
Should be easy enough to add the .* in the second string.

Answer 3

This code is in C# as I don't know PHP but should be easy to understand.
int index1 = 0, index2 = 0;
while (index1 < str1.Length && index2 < str2.Length)
{
if (str1[index1] == str2[index2]) index2++;
index1++;
}
if (index2 == str2.Length) return true;

Answer 4

Imagine that your string is array and after that use array_diff function.
http://hu2.php.net/array_diff
$str1 = "HEADINGLEY";
$str2 = "HDNGLY";
$arr1 = str_split($str1, 1);
$arr2 = str_split($str2, 1);
$arr2_uniques = array_diff($arr2, $arr1);
return array() === $arr2_uniques;

Answer 5

Possibly this snippet will do it:
var contains = true;
for (var i=0; i < str2.length; i++)
{
var char = str2.charAt(i);
var indexOfChar = str1.indexOf(char);
if (indexOfChar < 0)
{
contains = false;
}
str1 = str1.substr(indexOfChar);
}

Answer 6

You can use pre_match function, like that:
$split_str2 = str_split($str2);
// Create pattern from str2
$pattern = "/" . implode(".*", $split_str2) . "/";
// Find
$result = preg_match($pattern, $str1);

Answer 7

You can probably use some regular expression but be weary of strings that contained regex specific characters. This solution does it programmatically.
function contains_all_characters($str1, $str2)
{
$i1 = strlen($str1) - 1;
$i2 = strlen($str2) - 1;
while ($i2 >= 0)
{
if ($i1 == -1) return false;
if ($str1[$i1--] == $str2[$i2]) $i2--;
}
return true;
}

Answer 8

You can try:
$str = 'HEADINGLEY';
if (preg_match('/[^H]*H[^D]*D[^N]*N[^G]*G[^L]*L[^Y]*Y/', $str, $m))
var_dump($m[0]);
Update: Even better is to build regex like this and then use it:
$str = 'HEADINGLEY';
$pattern = 'HDNGLY';
$regex = '#' . preg_replace('#(.)#', '[^$1]*$1', $pattern) . '#';
if (preg_match($regex, $str, $m))
var_dump($m[0]);
OUTPUT:
string(10) "HEADINGLEY"