Question: i want to add `utm_source=twitter` in the of the links

i have a link let say
<http://abcd.com/news?id=1>

it need to be `http://abcd.com/news?id=1&utm_source=twitter`

if <http://abcd.com/news/1>

it need to be 

```
http://abcd.com/news/1?utm_source=twitter

```

any idea?

Answer: 
To check if your link already has URL parameters on the end of it, look for the ? character in the URL. If it's there, use a & instead.

```
$link = 'http://abcd.com/news?id=1'; // or http://abcd.com/news
$join_char = strpos($string, '?') !== -1 ? '&' : '?'; // determine if we need & or ?
$link .= $join_char . 'utm_source=twitter';

```
You can check if the URL already contains a query string and branch your logic accordingly:

```
if (strpos($url, '?') === FALSE) {
    $url .= '?utm_source=twitter';
} else {
    $url .= '&utm_source=twitter';
}

```