Edit all odd words in string to upper case - php

Question

I need to edit all odd words to upper case.
Here is sample of imput string:
very long string with many words
Expected output:
VERY long STRING with MANY words
I have this code, but it seams to me, that I can do it in better way.
<?php
$lines = file($_FILES["fname"]["tmp_name"]);
$pattern = "/(\S[\w]*)/";
foreach($lines as $value)
{
$words = NULL;
$fin_str = NULL;
preg_match_all($pattern, $value, $matches);
for($i = 0; $i < count($matches[0]); $i = $i + 2){
$matches[0][$i] = strtoupper($matches[0][$i]);
$fin_str = implode(" ", $matches[0]);
}
echo $fin_str ."<br>";
P.S. I need to use only preg_match function.

Answer 1

Here's a preg_replace_callback example:
<?php
$str = 'very long string with many words';
$newStr = preg_replace_callback('/([^ ]+) +([^ ]+)/',
function($matches) {
return strtoupper($matches[1]) . ' ' . $matches[2];
}, $str);
print $newStr;
// VERY long STRING with MANY words
?>
You only need to match the repeating pattern: /([^ ]+) +([^ ]+)/, a pair of words, then preg_replace_callback recurses over the string until all possible matches are matched and replaced. preg_replace_callback is necessary to call the strtoupper function and pass the captured backreference to it.
Demo

Answer 2

If you have to use regular expressions, this should get you started:
$input = 'very long string with many words';
if (preg_match_all('/\s*(\S+)\s*(\S+)/', $input, $matches)) {
$words = array();
foreach ($matches[1] as $key => $odd) {
$even = isset($matches[2][$key]) ? $matches[2][$key] : null;
$words[] = strtoupper($odd);
if ($even) {
$words[] = $even;
}
}
echo implode(' ', $words);
}
This will output:
VERY long STRING with MANY words

Answer 3

You may don't need regex simply use explode and concatenate the string again:
<?php
function upperizeEvenWords($str){
$out = "";
$arr = explode(' ', $str);
for ($i = 0; $i < count($arr); $i++){
if (!($i%2)){
$out .= strtoupper($arr[$i])." ";
}
else{
$out .= $arr[$i]." ";
}
}
return trim($out);
}
$str = "very long string with many words";
echo upperizeEvenWords($str);
Checkout this DEMO