avoiding network issues between cURL calls - php

Question

Am trying to include two cURL command blocks. The second block depends on a value returned by the first block. I know that there could be network issues in trying to establish cURL calls between servers. The value returned by the first block will be saved in a database. What I want to know is how to write the syntax on the PHP file that will execute both cURL command blocks, so that when the value is returned by the first block I could start the second block, keeping in mind that there could be network problems. I know how to write the cURL command blocks. I just need that part that will avoid network issues. Here is what I was thinking: (inside the PHP file)
$default = "default value";
$a = $default;
//first block executes initializing $a
$a = "value returned by first block. Already saved to database";
//second block can't execute until this value is not set to default value
while($a != $default){
//second block executes
//somewhere to the end of second block
$result = curl_exec($ch); //where $ch is the handle for my cURL call
//exiting the while loop:
if(isset($result))exit(0); //don't know if this is the proper way of exit
//a while loop inside a PHP script
}
Please let me know if this seems to be correct or how can I improve it. One more thing, since I am fairly new to PHP, how do you comment out syntax lines in PHP?
Do you use // as in JAVA?
thank you

Answer 1

cURL is not asynchronous so you don't have to worry about making your code wait for it to finish. That is, PHP will not execute the lines after curl_exec() until the cURL request has completed. Something like this should work for you:
$result = curl_exec($ch);
if($result !== false){
//Do Stuff on successful curl
}
else{
echo curl_error($ch); //print the curl error
}
Also, the way to exit a while loop is break;, if you only want to skip the current iteration, use continue;