Using curl_errno() in PHP to Retrieve cURL Error Codes

When making network requests in PHP, errors such as timeouts or DNS failures can occur; the curl_errno() function allows developers to retrieve the error code of the most recent cURL operation.

1. Function Overview

The curl_errno() function accepts a cURL handle resource and returns the error number of the last request; it returns 0 if no error occurred.

int curl_errno ( resource $ch )

2. Example Code

The following example demonstrates initializing a cURL handle, setting options, executing the request, checking for errors with curl_errno(), outputting either the error code or a success message, and finally 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 and configures it, then runs curl_exec() to perform the request and stores the result in $response. Afterwards curl_errno() is called to determine whether an error occurred; if so, the error code is retrieved and displayed, otherwise a success message is printed. Finally curl_close() releases the handle.

3. Common Error Codes

Typical cURL error numbers and their meanings include:

1. CURLE_COULDNT_CONNECT (7): could not connect to host

2. CURLE_OPERATION_TIMEDOUT (28): operation timed out

3. CURLE_COULDNT_RESOLVE_HOST (6): could not resolve host

4. CURLE_SSL_CONNECT_ERROR (35): SSL connection error

5. 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 PHP applications.