Using curl_errno() in PHP to Retrieve cURL Error Codes

When making network requests, errors such as connection timeouts or DNS failures can occur; PHP provides the curl_errno() function to retrieve the error code of a cURL request. This article introduces the usage of curl_errno() and provides example code.

1. Function Overview

curl_errno()

is a PHP function that returns the error code of the most recent cURL operation for a given cURL handle. int curl_errno ( resource $ch ) The function accepts a cURL handle as its argument and returns 0 if no error occurred, otherwise a non‑zero error code.

2. Example Code

The following example demonstrates initializing a cURL handle, setting options, executing the request, checking for errors with curl_errno(), and closing the handle.

<?php<br/>// Initialize a cURL handle<br/>$ch = curl_init();<br/><br/>// Set cURL options<br/>curl_setopt($ch, CURLOPT_URL, "http://www.example.com");<br/>curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);<br/><br/>// Execute the request<br/>$response = curl_exec($ch);<br/><br/>// Check for errors<br/>if (curl_errno($ch)) {<br/>    // Get error code<br/>    $error_code = curl_errno($ch);<br/>    echo "cURL request error, code: " . $error_code;<br/>} else {<br/>    // No error
    echo "cURL request succeeded!";<br/>}<br/><br/>// Close the handle<br/>curl_close($ch);<br/>?>

In this example, after initializing the handle and setting options (such as the request URL and whether to return the response), curl_exec() performs the request and stores the result in $response. Then curl_errno() checks for errors; if an error exists, the error code is retrieved and displayed, otherwise a success message is shown. Finally, curl_close() releases the handle.

3. Common Error Codes

Some frequently encountered cURL error codes and their meanings are:

1. CURLE_COULDNT_CONNECT (7) : Unable to connect to the host.

2. CURLE_OPERATION_TIMEDOUT (28) : Operation timed out.

3. CURLE_COULDNT_RESOLVE_HOST (6) : Failed to resolve the host name.

4. CURLE_SSL_CONNECT_ERROR (35) : SSL connection error.

5. CURLE_OK (0) : No error occurred.

Conclusion

By using the curl_errno() function, developers can easily obtain cURL error codes and implement appropriate error‑handling logic, thereby enhancing the stability and reliability of their applications.