Convert a number to hex string

[Davy Mitchell]

Hi Folks,

I'm looking to convert an int to a hex string. Neither num, int or string seem to have a suitable method.

There appears to be a method in the library fixednum's int32 class but that library deprecated apparently? Still in API docs tho.

Apologies if I am missing something obvious.

Thanks,

Davy

[William Hesse]

int.toRadixString(16) should convert an int to a hex string, though it does not add a leading 0x.

Then String.toUpperCase can be used if you want A..F instead of a..f to represent the hex digits.

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William Hesse

[Davy Mitchell]

Thanks for the fast reply William. Looks like what I need.

[Davy Mitchell]

Thanks for that. I was thinking this was easier in other languages but looks about the same as .Net/Python. Confusing having fixednum in the docs though.

*ponders feature request and/or bug*

:-)

Davy

On 24 June 2013 13:10, mezoni <andrew...@gmail.com> wrote:

Here are more advanced example.

void main() { var unicode = charToUnicode(16); print(unicode); } String charToUnicode(int char) { if(char == null || char < 0 || char > 0xfffffffff) { throw new ArgumentError('c: $char'); } var hex = char.toRadixString(16); var length = hex.length; var count = 0; if(char <= 0xffff) { count = 4; } else { count = 8; } for(var i = 0; i < count - length; i++) { hex = '0$hex'; } return '\\u$hex'; }

Output:

\u0010

[Alex Tatumizer]

String charToUnicodeString(int char) =>
  (char < 0 || char > 0xFFFFFF) ? throw new ArgumentError("out of Unicode range: $char") :  
  char <= 0xFFFF ? "\\u${(char+0x10000).toRadixString(16).substring(1)}" :
  "\\u{${char.toRadixString(16)}}";

I wonder if this is the shortest way to write it.

 

[Lasse R.H. Nielsen]

Shortest generating code or shortest output? 

The shortest output is \x.. for values < 256, \uxxxx for values < 65536 and \u{......} for the rest.

For generating code it's pretty good, but not as short as "\\u{${char.toRadixString(16)}}" :)

/L

 

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Lasse R.H. Nielsen - l...@google.com  

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[Alex Tatumizer]

That's what happens when one tries to solve unspecified problem :-)

There's a lot in dart itself and its libraries that suffers from the same malaise. Aforementioned "const" is an illustration :-)

Anyway, snippet takes advantage of very good feature of dart: you can throw exceptions in expressions.

this makes possible to write the whole if-else if-else if-... as a single expression, using ?: operator.

(Another feature that helps constructing cool expressions is double dot - really good idea).

Thanks for \x tip, I didn't know about it.