Using curl_errno() in PHP to Retrieve 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.

1. Function Overview

The curl_errno() function returns the last error number for the given cURL handle. Its signature is: int curl_errno ( resource $ch ) If no error occurred it returns 0; otherwise a non‑zero error code.

2. Example Code

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

<?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 error code
    $error_code = curl_errno($ch);
    echo "cURL request failed, error code: " . $error_code;
} else {
    // No error
    echo "cURL request succeeded!";
}

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

The script first creates a cURL handle, configures the URL and return option, runs curl_exec(), and stores the result in $response. It then uses curl_errno() to detect errors, prints the error code if any, or confirms success, and finally releases resources with curl_close().

3. Common Error Codes

Typical cURL error numbers and their meanings include:

CURLE_COULDNT_CONNECT (7): unable to connect

CURLE_OPERATION_TIMEDOUT (28): operation timed out

CURLE_COULDNT_RESOLVE_HOST (6): host could not be resolved

CURLE_SSL_CONNECT_ERROR (35): SSL connection error

CURLE_OK (0): no error

Conclusion

By using curl_errno(), developers can easily obtain the error code of a cURL request, enabling more precise error handling and improving the stability and reliability of backend applications.