PHP curl_exec Function

last modified April 11, 2025

The PHP curl_exec function executes a cURL session. It's used to perform HTTP requests and fetch data from remote servers. cURL supports various protocols like HTTP, HTTPS, FTP, and more.

Basic Definition

The curl_exec function executes the given cURL session. It returns the result on success, FALSE on failure. The function takes a cURL handle as its only parameter.

Syntax: curl_exec(CurlHandle $handle): mixed. The handle must be created with curl_init() and configured before execution. Always close the handle with curl_close() after use.

Basic GET Request

This example demonstrates a simple GET request to fetch data from a URL.

basic_get.php

<?php

declare(strict_types=1);

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, "https://jsonplaceholder.typicode.com/posts/1");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$response = curl_exec($ch);

if ($response === false) {
    echo "cURL Error: " . curl_error($ch);
} else {
    echo $response;
}

curl_close($ch);

This code fetches a sample post from JSONPlaceholder API. We set the URL and RETURNTRANSFER option to get the response as a string. Error handling is included to catch potential issues.

POST Request with Data

This example shows how to send a POST request with form data.

post_request.php

<?php

declare(strict_types=1);

$ch = curl_init();

$postData = [
    'title' => 'New Post',
    'body' => 'This is the content',
    'userId' => 1
];

curl_setopt($ch, CURLOPT_URL, "https://jsonplaceholder.typicode.com/posts");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);

$response = curl_exec($ch);

if ($response === false) {
    echo "cURL Error: " . curl_error($ch);
} else {
    echo "Response: " . $response;
}

curl_close($ch);

We create a POST request with form data. The CURLOPT_POST option sets the method, and CURLOPT_POSTFIELDS contains the data to send. The API returns the created resource as JSON.

Handling JSON Response

This example demonstrates proper handling of a JSON API response.

json_response.php

<?php

declare(strict_types=1);

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, "https://jsonplaceholder.typicode.com/users/1");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'Accept: application/json'
]);

$response = curl_exec($ch);

if ($response === false) {
    echo "cURL Error: " . curl_error($ch);
} else {
    $user = json_decode($response, true);
    echo "User name: " . $user['name'];
}

curl_close($ch);

We fetch a user object and decode the JSON response. The Accept header specifies we want JSON. After decoding, we can access the data as an associative array.

Setting Custom Headers

This example shows how to set custom HTTP headers for a request.

custom_headers.php

<?php

declare(strict_types=1);

$ch = curl_init();

$headers = [
    'Authorization: Bearer abc123',
    'Content-Type: application/json',
    'X-Custom-Header: value'
];

curl_setopt($ch, CURLOPT_URL, "https://api.example.com/protected");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

$response = curl_exec($ch);

if ($response === false) {
    echo "cURL Error: " . curl_error($ch);
} else {
    echo $response;
}

curl_close($ch);

We set multiple custom headers including an authorization token. Headers are passed as an array to CURLOPT_HTTPHEADER. This is common for APIs requiring authentication or specific content types.

Handling HTTPS with SSL Verification

This example demonstrates proper SSL certificate verification for HTTPS.

ssl_verification.php

<?php

declare(strict_types=1);

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, "https://secure.example.com/api");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_CAINFO, "/path/to/cacert.pem");

$response = curl_exec($ch);

if ($response === false) {
    echo "cURL Error: " . curl_error($ch);
} else {
    echo $response;
}

curl_close($ch);

We configure cURL to verify the SSL certificate. CURLOPT_SSL_VERIFYPEER enables peer verification, and CURLOPT_SSL_VERIFYHOST checks the hostname. For production, always use proper certificate verification.

Best Practices

Error Handling: Always check curl_exec return value.
Resource Cleanup: Close handles with curl_close.
SSL Security: Enable verification for HTTPS.
Timeouts: Set CURLOPT_TIMEOUT to avoid hanging.
Memory: Use CURLOPT_FILE for large downloads.

Source

PHP curl_exec Documentation

This tutorial covered the PHP curl_exec function with practical examples showing its usage for various HTTP request scenarios.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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