We discuss PHP today from the LAMP stack. PHP is embedded in HTML. It gets translated to HTML from the server before it reaches the client. PHP is wrapped with <?php , <? or <script language="php">
PHP works with virtually all web server software and most databases. PHP configuration is handled with the php.ini file. Single line comments start with #. Multi line printing starts with a label such as print <<< END or with quotes. PHP is whitespace and case sensitive. The data types include integers, doubles, boolean, NULL, strings etc. Variable scope includes local variables, function parameters, global and static variables. Like C, we have __LINE__, __FILE__, and __FUNCTION__  Loops are similar as well.
Arrays can be numeric, associative and multidimensional. Dot operator is used to concatenate strings. fopen, fclose, fread and filesize are some file methods. functions are declared with the function keyword such as
function writeMessage()
{
echo "Hello";
}
Reference passing can be done with the & operator both in declaration and invocation. Default values for function parameter can be set.

<?php

function cURLcheckBasicFunctions() 

{ 

  if( !function_exists("curl_init") && 

      !function_exists("curl_setopt") && 

      !function_exists("curl_exec") && 

      !function_exists("curl_close") ) return false; 

  else return true; 

} 



// declare

if( !cURLcheckBasicFunctions() ) print_r('UNAVAILABLE: cURL Basic Functions');

$apikey = 'your_api_key_here';

$clientId = 'your_client_id_here';

$clientSecret = 'your_client_secret_here';

$url = 'https://my.api.com?api_key='.$apikey;

$ch = curl_init($url);

$fields = array(

'user' => urlencode('user'));



//url-ify the data for the POST

$fields_string = '';

foreach($fields as $key=>$value) { $fields_string .= $key.'='.$value.'&'; }

rtrim($fields_string, '&');        

curl_setopt($ch, CURLOPT_URL, $url);

// curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC ) ; 

// curl_setopt($ch, CURLOPT_USERPWD, $credentials);

// curl_setopt($ch, CURLOPT_SSLVERSION, 3); 

curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);                        

curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);

curl_setopt($ch, CURLOPT_POST, count($fields));

curl_setopt($ch, CURLOPT_POSTFIELDS, $fields_string);



//execute post

if(curl_exec($ch) === false)

{

    echo 'Curl error: ' . curl_error($ch);

}

else

{

    echo 'Operation completed without any errors';

}



//close connection

curl_close($ch);

?> 

This is a sample REST call using curl and PHP