Mastering PHP curl_errno(): Retrieve and Handle cURL Error Codes

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

1. Function Overview

curl_errno()

is a PHP function that returns the error code of the most recent cURL request. It accepts a cURL handle as its parameter and returns 0 if no error occurred, otherwise a non‑zero error code.

int curl_errno(resource $ch)

2. Example Code

The following example demonstrates using curl_errno() to detect and handle errors.

<?php
// Initialize a cURL handle
$ch = curl_init();

// Set cURL options
curl_setopt($ch, CURLOPT_URL, "http://www.example.com");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

// Execute the request
$response = curl_exec($ch);

// Check for errors
if (curl_errno($ch)) {
    // Get the error code
    $error_code = curl_errno($ch);
    echo "cURL request failed, error code: " . $error_code;
} else {
    echo "cURL request succeeded!";
}

// Close the handle
curl_close($ch);
?>

In this example we initialize a cURL handle, set options such as the request URL and whether to return the response, execute the request with curl_exec(), and store the result in $response. We then call curl_errno() to check for errors; if an error occurred we retrieve the code with curl_errno() and output a message. If no error occurred we output a success message. Finally, curl_close() releases the handle.

3. Common Error Codes

Below are some common cURL error codes and their meanings:

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

CURLE_OPERATION_TIMEDOUT (28): Operation timed out.

CURLE_COULDNT_RESOLVE_HOST (6): Could not resolve host.

CURLE_SSL_CONNECT_ERROR (35): SSL connection error.

CURLE_OK (0): No error occurred.

Conclusion

By using the curl_errno() function, developers can easily obtain the error code of a cURL request, allowing them to implement appropriate error handling strategies and improve the stability and reliability of their applications.