Guía de Conversión de cURL a PHP

<?php

$curl = curl_init();

curl_setopt_array($curl, [
    CURLOPT_URL => 'https://api.example.com/v1/orders',
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_ENCODING => '',
    CURLOPT_MAXREDIRS => 10,
    CURLOPT_TIMEOUT => 30,
    CURLOPT_FOLLOWLOCATION => false,
    CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_HTTPHEADER => [
        'Content-Type: application/json',
        'Authorization: Bearer sec_tok_99887766'
    ],
    CURLOPT_POSTFIELDS => json_encode({
    "order_id": "ORD-5021",
    "amount": 149.99,
    "currency": "USD",
    "items": [
        {
            "sku": "A10",
            "qty": 2
        }
    ]
})
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
    echo "cURL Error #: " . $err;
} else {
    echo $response;
}