chetrasho (OP)
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May 22, 2011, 05:32:55 PM |
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Hi,
I'm writing a PHP script for bitcoins. I need a regex to check if a string is a valid number of bitcoins.
I've been trying stuff like [0-9]{0,8}\.[0-9]{0,8} but I know that's not really right. I suck at regexes...
Any help would be greatly appreciated...
Thanks
TRSH0
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Once a transaction has 6 confirmations, it is extremely unlikely that an attacker without at least 50% of the network's computation power would be able to reverse it.
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kseistrup
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May 22, 2011, 05:38:32 PM |
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Would it be easier to convert the amount to a float, then assert that the number is positive and <= 21E6?
Cheers,
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Klaus Alexander Seistrup
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chetrasho (OP)
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May 22, 2011, 05:54:26 PM |
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Well, the variable $bitcoinamount is coming form post data $_POST['bitcoinamount']. So it's not necessarily a number to begin with.
I guess I could do something like
if ( is_float($ba) && $ba <= 21E6 && num_decimals($ba) <= 8 ) { return true; }
But I need a num_decimals() function.
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kseistrup
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May 22, 2011, 06:00:47 PM |
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I don't speak PHP, but in Python you could do something like: def num_decimals(amount_string):
(integer, decimals) = amount_string.split('.')
return len(decimals)
Cheers, |
Klaus Alexander Seistrup
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bittrader
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May 22, 2011, 06:29:20 PM |
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Something like this would probably work. $btc = $_POST['bitcoinamount'];
// Verify that the amount is (1) less than 21 million, (2) contains only numerals and an optional decimal point, and (3) contains a maximum of eight number after the decimal point.
if (preg_match( '/^[0-9]*\.?[0-9]{0,8}$/', $btc) && $btc <= 21000000)
echo "valid";
else
echo "fail";
Depending what you're doing, you might want to also verify that the amount isn't zero. |
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chetrasho (OP)
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May 22, 2011, 06:40:11 PM |
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Awesome. That's basically what I need, bittrader. Thank you so much!
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theymos
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May 22, 2011, 11:53:27 PM |
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I think this would work as a pure-regex solution: ^0*(1?[0-9]|20)?[0-9]{0,6}(\.[0-9]{0,8}0*)?$ |
1NXYoJ5xU91Jp83XfVMHwwTUyZFK64BoAD
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chetrasho (OP)
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May 23, 2011, 01:51:10 AM |
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Nice. Thank you. Regexs are pretty sweet. It's just a few characters but over time I hope your work helps tons of developers...
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nopara73
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April 01, 2016, 06:10:46 PM |
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I think this would work as a pure-regex solution: ^0*(1?[0-9]|20)?[0-9]{0,6}(\.[0-9]{0,8}0*)?$This is a good starting point, but it is not perfect. (I am not going to give the solution, but I want to note it before someone starts to use it blindly based on a quick google search.) For example it matches the input: 0000000000000000000000000000000009999999.00000000000000000000000000000000000000 0000000000000000 Also it doesn't let the "," to be used instead of ".", in some case you might want that that. |
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