CODEWITHSUNDEEP
phphtmlhostingecho
Jason
Jason

Reputation: 185

PHP script behaves differently in browser

I am trying to list the current USD price of an item in mBTC (millibitcoin) using the Coinbase API. Here is my code:

<?php
    $string = file_get_contents('https://coinbase.com/api/v1/prices/spot_rate');
    $result = json_decode($string);
    $spot = $result->amount;
    $price = 2; //change this to your USD value
    $whole = substr($price/$spot, 4, -13);
    $dec = substr($price/$spot, 4, -12);
    echo $whole.'.'.$dec.' mBTC';
?>

It works flawlessly in Coderunner (OS X app for development) but fails when run on my hosting server. Link to browser script: http://bitcoindecals.com/oval-price.php

I am using Dynadot Advanced hosting and it includes PHP support. I know that PHP is being utilized because "mBTC" is being echoed correctly. It just appears the $whole and $dec variables aren't being set for some reason. Is there a way to get this to work?

Upvotes: 0

Views: 199

Answers (3)

Peter van der Wal
Peter van der Wal

Reputation: 11786

You're making a few (extremly wrong) assumptions in the following lines:

$whole = substr($price/$spot, 4, -13);
$dec = substr($price/$spot, 4, -12);

$price / $spot is treated as a string and you assume it will be in the format

'0.0019XXXXXXXXXXXX' // 12 x's (unkown numbers)

What if Bitcoin is doing really bad and the rate exeeds 10 mBTC per USD? $price / $spot will be something like:

'0.0108491827849201'; // (10.8 mBTC)
$whole = substr('0.0108491827849201', 4, -13); // Will be '0'
$dec = substr('0.0108491827849201', 4, -12); // Will be '08'
echo $whole . '.' . $dec . ' mBTC'; // Will echo '0.08 mBTC'

What if, due to rounding or accuracy (! this is what you're seeing in your server - most likely because your OSX is 64bit, your server 32bit or vice-versa !), the string-length of $price / $spot is less than 18 characters:

'0.0019564521431';
$whole = substr('0.0019564521431', 4, -13);
// Meaning: start at position 4, stop at 13 characters counting from the end
// 13 characters from the end is here: '0.0019564521431'
//                                       ^
// so the stop-position is before the start-position, resulting in an empty
// string. Same with $dec.
echo $whole . '.' . $dec . ' mBTC'; 
// Will echo empty-string . '.' . empty-string . ' mBTC': '. mBTC'

Long story short: never ever treat numbers as a string (unless you have no other options and you are fully aware of what you are doing). Following code will work, and will give the correct output:

echo number_format($price / $spot * 1000, 1);
// multiply by 1000: BTC to milli-BTC
// , 1: One digit after the dot

For a full explanation of number_format see: http://php.net/number_format

Upvotes: 1

jingyu
jingyu

Reputation: 115

you can't crawler the data from https://coinbase.com/api/v1/prices/spot_rate
so $string is empty!
do {
$string = file_get_contents('https://coinbase.com/api/v1/prices/spot_rate');
} while (!empty($string));
$result = json_decode($string);
$spot = $result->amount;
$price = 2; //change this to your USD value
if (isset($spot) or $spot == 0) {
echo "\$spot is not islet or 0";
} else {
$whole = substr($price/$spot, 4, -13);
$dec = substr($price/$spot, 4, -12);
echo $whole.'.'.$dec.' mBTC';
}

Upvotes: 0

Anirban
Anirban

Reputation: 580

I just executed the exact code in my WAMP server on windows.... It seemed to work perfectly smooth !!!

OUTPUT : 1.19 mBTC Is it what you expect????

I think your server is unable to access web pages, so, your php code variables are going vacant...try XAMP and check out ....

Thanks....

Upvotes: 0

Related Questions