PHP curl_errno() Function Explained: How to Retrieve cURL Request Error Codes

PHP curl_errno() Function Explained: How to Retrieve cURL Request Error Codes

When making network requests, developers often encounter various errors, such as connection timeouts, DNS resolution failures, and more. To effectively handle these errors, PHP provides a very useful function—curl_errno(), which helps developers retrieve the error codes for cURL requests. This article will explain how to use the curl_errno() function and provide example code.

1. Function Overview

curl_errno() is a PHP function that retrieves the error code from the most recent cURL request. Its definition is as follows:

int curl_errno ( resource $ch )

This function accepts a cURL handle as its parameter and returns the error code for the most recent cURL request. If no error occurred, it returns 0; if an error occurred, it returns a non-zero error code.

2. Example Code

Below is an example that demonstrates how to use the curl_errno() function to check and retrieve error codes from a cURL request:

<?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 cURL request
$response = curl_exec($ch);

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

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

In the above example, we first initialize a cURL handle and set various cURL options (such as the requested URL and whether to return the response content). We then execute the cURL request using the curl_exec() function and store the result in the $response variable.

Next, we use the curl_errno() function to check whether any errors occurred. If an error occurred, we retrieve the error code and display an error message; otherwise, we output "cURL request succeeded!".

Finally, we close the cURL handle using curl_close() to release resources.

3. Common Error Codes

Here are some common cURL error codes and their meanings:

1. CURLE_COULDNT_CONNECT (7): Failed to connect
2. CURLE_OPERATION_TIMEDOUT (28): Operation timeout
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 occurred

These error codes help developers diagnose and address various issues that may arise with cURL requests, improving the reliability and stability of applications.

Conclusion

By using the curl_errno() function, developers can easily retrieve error codes from cURL requests and handle errors accordingly. This feature plays a crucial role in optimizing the reliability and stability of network requests in real-world development.

We hope this article has helped you understand and use the curl_errno() function effectively, and provided useful insights for your development projects!