Replacing all occurrences of a string with values from an array

Question

I am parsing a string before sending it to a DB. I want to go over all <br> in that string and replace them with unique numbers that I get from an array followed by a newLine.

For example:

str = "Line <br> Line <br> Line <br> Line <br>"
$replace = array("1", "2", "3", "4");

my function would return 
"Line 1 \n Line 2 \n Line 3 \n Line 4 \n"

Sounds simple enough. I would just do a while loop, get all the occurances of <br> using strpos, and replace those with the required numbers+\n using str_replace.

Problem is that I always get an error and I have no idea what I am doing wrong? Probably a dumb mistake, but still annoying.

Here is my code

$str     = "Line <br> Line <br> Line <br> Line <br>";
$replace = array("1", "2", "3", "4");
$replaceIndex = 0;

while(strpos($str, '<br>') != false )
{
    $str = str_replace('<br>', $replace[index] . ' ' .'\n', $str); //str_replace, replaces the first occurance of <br> it finds
    index++;
}

Any ideas please?

Thanks in advance,

Answer 1

I would use a regex and a custom callback, like this:

$str = "Line <br> Line <br> Line <br> Line <br>";
$replace = array("1", "2", "3", "4");
$str = preg_replace_callback( '/<br>/', function( $match) use( &$replace) {
    return array_shift( $replace) . ' ' . "\n";
}, $str);

Note that this assumes we can modify the $replace array. If that's not the case, you can keep a counter:

$str = "Line <br> Line <br> Line <br> Line <br>";
$replace = array("1", "2", "3", "4");
$count = 0;
$str = preg_replace_callback( '/<br>/', function( $match) use( $replace, &$count) {
    return $replace[$count++] . ' ' . "\n";
}, $str);

You can see from this demo that this outputs:

Line 1 Line 2 Line 3 Line 4