string manipulation?

[avi123]

Hello,

I was wondering if there is a function that does the follwoing manipulation over a string containing a number:


Input :
std::string sMyNumber = "1234.56"
MyFunc(&sMyNumber);

Output:
1,234.56

in short: adding , in long in numbers

thanks
avi

[avi123]

well I did some research, and found out that there isn't such a function in stl

so I wrote these function, what do you think?

string CGeneral::AddComma(string* psStr)
{

string sTmp = *psStr;

string::size_type pos = sTmp.find('.');

//check if the string holds decimal point
if (pos != string::npos)
sTmp = sTmp.substr(0,pos);

reverse(sTmp.begin(), sTmp.end());

string sResult;

while(sTmp.length() > 3)
{
//group them, 3 at a time
sResult += sTmp.substr(0,3) + _T(",");
sTmp.erase(0,3);
}
sResult += sTmp;

reverse(sResult.begin(), sResult.end());

//add the .### part
if (pos != string::npos)
sResult += psStr->substr(pos,psStr->length());

return sResult;
}

[Paul McKenzie]

Originally posted by avi123
well I did some research, and found out that there isn't such a function in stl

Your solution will look wierd for countries that use "." or spaces for the thousands separator (this is directed to the OP as well). At the very least, you should get the locale information to determine what are the different separators for a number.

Yves the moderator did some more research, and you can achieve it using the C++ library. An example from MSDN:

// num_put_put.cpp
// compile with: /EHsc
#include <locale>
#include <iostream>
#include <sstream>
using namespace std;
int main( )
{
   locale loc( "german_germany" );
   basic_stringstream<char> psz2;
   ios_base::iostate st = 0;
   long double fVal;
   cout << "The thousands separator is: " 
        << use_facet < numpunct <char> >(loc).thousands_sep( ) 
        << endl;

   psz2.imbue( loc );
   use_facet < num_put < char > >
      ( loc ).put(basic_ostream<char>::_Iter(psz2.rdbuf( ) ),
                    psz2, st, fVal=1000.67);

   if ( st & ios_base::failbit )
      cout << "num_put( ) FAILED" << endl;
   else
      cout << "num_put( ) = " << psz2.rdbuf( )->str( ) << endl;
}

BTW avi123, not everything is STL. There are many parts of C++ library that have nothing to do with STL, as Yves solution demonstrates. Locales are not part of STL. So if you are looking for a solution, and you turn to your STL reference, you won't find it. If you turn to the C++ library reference referring to locale information, then you will find what you're looking for.

Regards,

Paul McKenzie