<?
$str = "This could be your opportunity to start with one website and end up with [one] a great enterprise.";
$str2 = str_replace("one", "first", $str);
echo $str2; // This could be your opportunity to start with first website and end up with [one] a great enterprise.
?>
<?
$str = "This could be your opportunity to start with one website and end up with [one] a great enterprise.";
$str2 = str_replace("one", "first", $str);
$str3 = str_replace("[first]", "[one]", $str2);
echo $str2."<br>".$str3;
?>
<?
$str = "This could be your opportunity to start with one website and end up with [done] a great enterprise.";
$str2 = str_replace("one", "first", $str);
echo $str2; // This could be your opportunity to start with first website and end up with [done] a great enterprise.
?>
<?
$str = "This could be your opportunity to start with one website and end up with [done] a great enterprise.";
$str2 = explode(" ",$str);
$str3 = "";
for($i < 0 ; $i < count($str2);$i++){
if($str2[key($str2)]=='one'){
$str3 .= " first ";
}else{
$str3 .= $str2[key($str2)]." ";
}
next($str2);
}
echo $str3;
?>