Formatting number strings?

[mburke]

I have a number as a string

string aaa;
//assign string number
aaa = "333333333";

And I would like to reformat the number to make it more readable...
//reformat
aaa = "333,333,333"

Is there an easy way to do this?

[David Smulders]

Maybe something like this?

void MakeNiceString(CString *nStr,int nSpace,CString nChar)
{
    int y = nStr->GetLength();    
    int iCharCount = 0;

    while (y > 0) 
    {
        if(iCharCount == nSpace)
        {
            iCharCount = 0;
            nStr->Insert(y,nChar);
        }

        iCharCount++;
        y--;
    }
}

CString aaa = "3333333333";
MakeNiceString(&aaa,3,",");
AfxTrace(aaa); // 3,333,333,333 

[Kheun]

Just wondering if there is any C++ way where we can use std::locale and std::facet to achieve the same thing. Unfortunately, so far my google search has not find any good example.

[Kheun]

Okay, just manage to get this code to work on VC++.Net. However, on VC++6, dvalue is not being displayed properly. Guess that is because VC++6 is not as standard complaint as compared to VC++.Net.

#include <locale>
#include <iostream>

using namespace std;

int main()
{
    int ivalue = 10000;
    double dvalue = 20000.202;

    cout.imbue( locale("enu") );
    cout << ivalue << endl;
    cout << dvalue << endl;

    cout.imbue( locale::classic() );  // Restore to classic C locale.

    return 0;
}

[usmanqadri]

This will insert commas on exact locations

void FormatNumber(CString& vol)
{
vol.TrimLeft();
vol.TrimRight();

int len = vol.GetLength();


for(int i = len - 3 ; i > 0 ; i -= 3)
{
vol.Insert(i,",");

}
}

[NMTop40]

will these people please STOP offering solutions using MFC! This is a non-MFC forum and the original poster did not specify MFC.

Now, how to insert a comma every 3rd character from the right? (I like Kheun's idea but we know we have started with a string and we'll assume we know it's numeric and want a comma and not any other symbol).

Now let's go for an old-fashioned for-loop:

inserting from the front...

std::string s;
len = s.length();
for ( int i = ((len-1)%3) + 1; i < len; i+=4, ++len )
{
  s.insert( i, 1, ',' );
}

from the back I think this will work:

std::string s;
len = s.length();
for ( int i= len - 3; i > 0; i -= 3 )
{
  s.insert( i, 1, ',' );
}

Anyone who can come up with wonderful insert_iterator and transform or whatever to do something like this will get prizes for elegance.

[mburke]

Thanks for all the help, guys.

[mburke]

Well, there is a new wrinkle in this. I was not told this, the numbers are dollar amounts with cents.

so 100000.00 needs to look like 100,000.00

[Marc G]

#include <locale>
#include <iostream>

using namespace std;

int main()
{
    int ivalue = 10000;
    double dvalue = 20000.202;

    cout.imbue( locale("enu") );
    cout << ivalue << endl;
    cout << dvalue << endl;

    cout.imbue( locale::classic() );  // Restore to classic C locale.

    return 0;
}

You use a hardcoded "enu" and you restore to ::classic which might be wrong.
Better:

#include <iostream>
#include <locale>
#include <iomanip>

using namespace std;

int main()
{
  locale loc("");
  locale loc_previous = cout.imbue(loc);
  cout.precision(2);
  cout << std::fixed;
  double d = 2002.256530;
  cout << d << std::endl;
  cout.imbue(loc_previous);
  cout << d << std::endl;

  return 0;
}

[mburke]

Marc, I need to toss the formatted number into a string. It is going to be later written out to a file.

[Marc G]

Then use a stringstream.

  stringstream ss;
  locale loc("");
  locale loc_previous = ss.imbue(loc);
  ss.precision(2);
  ss << std::fixed;
  double d = 2002.256530;
  ss << d << std::endl;
  ss.imbue(loc_previous);

  // Get the string from the stringstream:
  ss.str();

[mburke]

I am having trouble using streams in this project. I get linker errors in libcpd.lib. The C++ streams have a conflict with the MySql lib. Is there another solution?

[Marc G]

Could you post some of the errors?

[mburke]

To link in mysqlclient.lib, I had to tell the linker to ignore LIBCD.lib or I get link redef errors.

So if I put this in

ifstream a("lala.txt");

Here are the link errors...

ibcpd.lib(xdebug.obj) : error LNK2019: unresolved external symbol __malloc_dbg referenced in function "void * __cdecl operator new(unsigned int,struct std::_DebugHeapTag_t const &,char *,int)" (??2@YAPAXIABU_DebugHeapTag_t@std@@PADH@Z)
libcpd.lib(locale.obj) : error LNK2001: unresolved external symbol __malloc_dbg
libcpd.lib(_tolower.obj) : error LNK2001: unresolved external symbol __malloc_dbg
libcpd.lib(xwcsxfrm.obj) : error LNK2019: unresolved external symbol __malloc_dbg referenced in function __Wcsxfrm
libcpd.lib(xdebug.obj) : error LNK2019: unresolved external symbol __free_dbg referenced in function "void __cdecl operator delete(void *,struct std::_DebugHeapTag_t const &,char *,int)" (??3@YAXPAXABU_DebugHeapTag_t@std@@PADH@Z)
libcpd.lib(xwcsxfrm.obj) : error LNK2001: unresolved external symbol __free_dbg
libcpd.lib(locale.obj) : error LNK2019: unresolved external symbol __realloc_dbg referenced in function "private: void __thiscall std::locale::_Locimp::_Addfac(class std::locale::facet *,unsigned int)" (?_Addfac@_Locimp@locale@std@@AAEXPAVfacet@23@I@Z)
libcpd.lib(xmbtowc.obj) : error LNK2001: unresolved external symbol _errno
libcpd.lib(xwcscoll.obj) : error LNK2001: unresolved external symbol _errno
libcpd.lib(xstrcoll.obj) : error LNK2001: unresolved external symbol _errno
libcpd.lib(locale.obj) : error LNK2001: unresolved external symbol _errno
libcpd.lib(xwctomb.obj) : error LNK2001: unresolved external symbol _errno
libcpd.lib(wlocale.obj) : error LNK2001: unresolved external symbol _errno
libcpd.lib(xlocale.obj) : error LNK2001: unresolved external symbol _errno
libcpd.lib(_tolower.obj) : error LNK2019: unresolved external symbol __chvalidator referenced in function __Tolower
libcpd.lib(_toupper.obj) : error LNK2019: unresolved external symbol __chvalidator referenced in function __Toupper
libcpd.lib(xmbtowc.obj) : error LNK2019: unresolved external symbol __CrtDbgReport referenced in function __Mbrtowc
Debug/EasyCheckup.exe : fatal error LNK1120: 6 unresolved externals

Build log was saved at "file://c:\EZTax Projects\EasyCheckup\Debug\BuildLog.htm"
EasyCheckup - 18 error(s), 3