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convert System::String to int or float

Posted on 2006-10-25
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Last Modified: 2008-02-01
Hi, I want to convert a string to a number.  I use code like this atm:

try {
      uint32_t d = System::Convert::ToUInt32(s);
      return(d);
} catch(...) {
      appendDebug(S"Input not a number");
      return(-1);
}

But I want to be able to handle numbers written as 0x12F3 for instance.  Less important is being able to handle scientific notation.

Is there any pre-made functions to do this?

Thanks,
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Question by:SilentBob
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6 Comments
 
LVL 48

Accepted Solution

by:
AlexFM earned 200 total points
ID: 17801681
For hexadecimal numbers use Int32.Parse Method (String, NumberStyles) with style parameter HexNumber.
0
 

Author Comment

by:SilentBob
ID: 17801688
how do I determine if my string is correctly formatted as a hex number?
0
 
LVL 48

Expert Comment

by:AlexFM
ID: 17801735
You cannot handle hexadecimal and decimal numbers in the same function. For example, string "123" can be both hexadecimal or decimal.
Int32.Parse Method throws exception if string doesn't contain valid number. For example, if you use HexNumber parameter and string is not formatted correctly, FormatException is thrown.
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Author Comment

by:SilentBob
ID: 17810460
When I use:

uint32_t d = System::Int32::Parse(s, System::Globalization::NumberStyles::AllowHexSpecifier);

or

uint32_t d = System::Int32::Parse(s, System::Globalization::NumberStyles::HexNumber);

I can convert strings like "1FF" fine, but I get an exception when they are entered as "0x1FF"

Must I manually parse the string?
0
 
LVL 48

Expert Comment

by:AlexFM
ID: 17811070
This looks strange, but AllowHexSpecifier style doesn' allow 0x:
Strings parsed using this style are not permitted to be prefixed with "0x" (MSDN).

You need to remove 0x manually before parsing.
0
 

Author Comment

by:SilentBob
ID: 17811089
yeah, I worked that out eventually; I manually parse them now.

Thanks for the help
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