Core files mod, will this cause unexpected errors?

I was thinking of a way, how to display price in default and selected currency and checkout with only default currency. Realized there was simple solution to my problem, it works on local copy of opencart. However i'm not sure if it will cause some unexpected problems or even abuse, a bit scary to apply to live shop I'm missing something here?

Here is what i did:
1. In system\library\currency.php i added a default value to $currency, instead of ' '. 2. In catalog\controller\payment\pp_standard.php changed this (i'm using only paypal): to simply 3. To display price in selected currency i'm simply adding this code in template files where i need

Not quite sure I fully understand what you are trying to do, but might be an easier way. You simply want to force your default currency for checkout, but want to show the customer selected currency on the site? Then the change you made in step 2 should be enough.

Qphoria wrote:Not quite sure I fully understand what you are trying to do, but might be an easier way. You simply want to force your default currency for checkout, but want to show the customer selected currency on the site? Then the change you made in step 2 should be enough.

Thanks, seems i can apply this change without worry. I made 1 and 3 steps, so customers won't be confused on checkout, why currency changed again etc. I want to show something like this:
Price: ¥8,000 ($100)

Well if it works then that is all that matters.
Tho you should make it as a vQmod script to avoid the code from being overwritten from and upgrade