Programming Forums > Application Development > C++

Robocop · Nov 7th, 2006, 3:34 PM

I want to get a float number obtained from an operation to show the comma for thousands, millions, etc. For example 12345.0 to 12,345.0

Is there a command like showcomma or something like that?

In VB you can just do Format(variable, "standard"), but what about C++?

kruptof · Nov 7th, 2006, 3:40 PM

for example if you were given the number 1500, and wanted to output 1500. i just did this on the fly so please do check over it.
if(num<=1000)
{
num=num / 1000;
out num;
out a comma;
num=num % 1000;
out num;
}

i think you need to something as similar as above..........you could use a switch statement instead of an if statement.

Narue · Nov 7th, 2006, 6:54 PM

>Is there a command like showcomma or something like that?
No, but it's easy to create your own facet that does precisely that:

(Toggle Plain Text)

#include <iostream>
#include <locale>

template <typename CharT>
class numfmt: public std::numpunct<CharT> {
  CharT sep_; // Character to separate groups
  int group_; // Number of characters in a group
public:
  numfmt ( CharT sep, int group ): sep_ ( sep ), group_ ( group ) { }
private:
  CharT do_thousands_sep() const { return sep_; }
  std::string do_grouping() const { return std::string ( 1, group_ ); }
};

int main()
{
  numfmt<char> *fmt = new numfmt<char> ( ',', 3 );

  std::cout.imbue ( std::locale ( std::locale(), fmt ) );

  for ( double n = 0, i = 1; n < 10; n++, i *= 10 )
    std::cout<< std::fixed << i <<'\n';
}

Game_Ender · Nov 8th, 2006, 1:00 PM

Wow that was a cool trick, that looks much easier to do than it would be in C. To bad its pretty obscure, I need a good resource for all these odd corners of the STL.

Cache · Nov 8th, 2006, 1:59 PM

Quote:

Originally Posted by Game_Ender

Wow that was a cool trick, that looks much easier to do than it would be in C. To bad its pretty obscure, I need a good resource for all these odd corners of the STL.

The "odd corners " are explained in "The C++ Standard Library: A Tutorial and Reference". Specifically chapter 13.8 and the whole of chapter 14 in this case.

http://www.amazon.com/C++-Standard-L.../dp/0201379260

Nov 7th, 2006, 3:34 PM	#1
Robocop Programmer Join Date: Sep 2004 Posts: 50 Rep Power: 5	Showing Comma I want to get a float number obtained from an operation to show the comma for thousands, millions, etc. For example 12345.0 to 12,345.0 Is there a command like showcomma or something like that? In VB you can just do Format(variable, "standard"), but what about C++?

Nov 7th, 2006, 6:54 PM	#3
Narue Professional Programmer Join Date: Sep 2005 Posts: 419 Rep Power: 4	>Is there a command like showcomma or something like that? No, but it's easy to create your own facet that does precisely that: (Toggle Plain Text) #include <iostream> #include <locale> template <typename CharT> class numfmt: public std::numpunct<CharT> { CharT sep_; // Character to separate groups int group_; // Number of characters in a group public: numfmt ( CharT sep, int group ): sep_ ( sep ), group_ ( group ) { } private: CharT do_thousands_sep() const { return sep_; } std::string do_grouping() const { return std::string ( 1, group_ ); } }; int main() { numfmt<char> fmt = new numfmt<char> ( ',', 3 ); std::cout.imbue ( std::locale ( std::locale(), fmt ) ); for ( double n = 0, i = 1; n < 10; n++, i = 10 ) std::cout<< std::fixed << i <<'\n'; } #include <iostream> #include <locale> template <typename CharT> class numfmt: public std::numpunct<CharT> { CharT sep_; // Character to separate groups int group_; // Number of characters in a group public: numfmt ( CharT sep, int group ): sep_ ( sep ), group_ ( group ) { } private: CharT do_thousands_sep() const { return sep_; } std::string do_grouping() const { return std::string ( 1, group_ ); } }; int main() { numfmt<char> fmt = new numfmt<char> ( ',', 3 ); std::cout.imbue ( std::locale ( std::locale(), fmt ) ); for ( double n = 0, i = 1; n < 10; n++, i = 10 ) std::cout<< std::fixed << i <<'\n'; } __________________ Even if the voices aren't real, they have some pretty good ideas.

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Nov 8th, 2006, 1:00 PM	#4
Game_Ender Professional Programmer Join Date: May 2006 Location: Maryland, USA Posts: 306 Rep Power: 3	Wow that was a cool trick, that looks much easier to do than it would be in C. To bad its pretty obscure, I need a good resource for all these odd corners of the STL.

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Programming Forums > Application Development > C++

Showing Comma