$string = " Some string ";
//the output should look like this
$output = "___Some string__";
So each leading and trailing whitespace replaced by underscore.
I found the regex for this in C here: Replace only leading and trailing whitespace with underscore using regex in c# but i couldn't make it work in php.
You could use a replace like:
$output = preg_replace('/\G\s|\s(?=\s*$)/', '_', $string);
\G matches at the beginning of the string or at the end of the previous match, (?=\s*$) matches if the following is only whitespace at the end of the string.
So this expression matches each of the spaces and replaces them with a _.
You can use regex with look ahead as Qtax suggested. An alternate solution using preg_replace_callback is : http://codepad.org/M5BpyU6k
<?php
$string = " Some string ";
$output = preg_replace_callback("/^\s+|\s+$/","uScores",$string); /* Match leading
or trailing whitespace */
echo $output;
function uScores($matches)
{
return str_repeat("_",strlen($matches[0])); /* replace matches with underscore string of same length */
}
?>
This code should work. Let me know if it doesn't.
<?php
$testString =" Some test ";
echo $testString.'<br/>';
for($i=0; $i < strlen($testString); ++$i){
if($testString[$i]!=" ")
break;
else
$testString[$i]="_";
}
$j=strlen($testString)-1;
for(; $j >=0; $j--){
if($testString[$j]!=" ")
break;
else
$testString[$j]="_";
}
echo $testString;
?>
