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String to Double Conversion without using strtod() or atof()
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Join Date: Dec 2005
Posts: 5,850
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If strtod() works on target with a non-null pointer, then a simple wrapper function would save you an awful lot of re-inventing the wheel.
Oh, and file a bug report with the library maintainer as well. A NULL parameter for the endptr is valid.
Oh, and file a bug report with the library maintainer as well. A NULL parameter for the endptr is valid.
Very well...
After some e-mail traffic with the company, I am shocked with an odd answer. The pos terminal I am working on does not support double or float variable types
But I have to use them and I cannot find any solution except re-inventing the wheel. (The one who invented wheel didn't have a deadline I guess
)
After some e-mail traffic with the company, I am shocked with an odd answer. The pos terminal I am working on does not support double or float variable types
But I have to use them and I cannot find any solution except re-inventing the wheel. (The one who invented wheel didn't have a deadline I guess
) •
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Join Date: Dec 2005
Posts: 5,850
Reputation:
Solved Threads: 749
Makes sense really, you don't want floating point anywhere near currency.
If you've got a decimal point to deal with, then consider
A nice integer, which isn't going to suffer from rounding errors.
So long as you use a 4-byte int thoughout, then overflow isn't likely to be a problem for most reasonable currencies not experiencing hyper inflation.
If you've got a decimal point to deal with, then consider
dollars = strtoul( p, 10, &endp ); cents = strtoul( endp+1, 10, NULL ); amount = dollars * 100 + cents;
A nice integer, which isn't going to suffer from rounding errors.
So long as you use a 4-byte int thoughout, then overflow isn't likely to be a problem for most reasonable currencies not experiencing hyper inflation.
Right but it was only that easy if i wouldn't need to use 4 operations ( * / - + ) All except division will not cause much problem I guess.
Last edited by JCasso; Nov 28th, 2008 at 11:46 am.
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Originally Posted by JCasso 
Very well...
After some e-mail traffic with the company, I am shocked with an odd answer. The pos terminal I am working on does not support double or float variable types
But I have to use them and I cannot find any solution except re-inventing the wheel. (The one who invented wheel didn't have a deadline I guess
Look at SoftFloat library:
http://www.jhauser.us/arithmetic/SoftFloat.html
Have you any OS on your POS? Sometimes OS supports FP emulation. Old C compilers for MS-DOS, for example, supported emulated floating-points arithmetics.
I totaly forgat it sorry... Seems like this device does not have it.
About OS... You mean a known one? dont you? No this is a taiwan stuff
About OS... You mean a known one? dont you? No this is a taiwan stuff
. It was x86 16-bit processor so I have installed DR-DOS. My type Money was unsigned long (32-bit emulation). It's funny but it was CPU with FPU. |
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