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Posted 25 Jun 2002

XFormatNumber - A function to format numbers with commas

, 25 Jun 2002
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An easy-to-use function that provides locale-correct comma-formatting of numbers


Formatting of numeric values with commas looks nice, but sometimes commas are not the correct thousands separator - many countries use "." for thousands separator. To ensure the correct separator, the Win32 function GetNumberFormat() should be used. However, this API requires the setup of a decimal separator, thousands separator, digit grouping, etc., which can add many lines of code to do a simple thing.

After needing to use GetNumberFormat() one more time, I decide to make a simple function with defaults taken from the locale.

XFormatNumber Features

takes as input a numeric string, which may or may not contain decimal point and fractional digits. XFormatNumber is defined as

CString XFormatNumber(LPCTSTR lpszNumber, int nFracDigits)
The parameter lpszNumber is numeric string, and the nFracDigits parameter specifies whether to include fractional digits in the  returned CString: 0 means no fractional digits, >0 means return nFracDigits fractional digits, and -1 means return however many fractional digits are contained in the numeric string.

XFormatNumber Demo

The demo app shows results for various formatting options:

m_List.AddString(XFormatNumber(_T("1"), -1));
m_List.AddString(XFormatNumber(_T("10"), -1));
m_List.AddString(XFormatNumber(_T("100"), -1));
m_List.AddString(XFormatNumber(_T("1000"), -1));
m_List.AddString(XFormatNumber(_T("10000"), -1));
m_List.AddString(XFormatNumber(_T("100000"), -1));
m_List.AddString(XFormatNumber(_T("1000000"), -1));
m_List.AddString(XFormatNumber(_T("10000000"), -1));
m_List.AddString(XFormatNumber(_T("100000000"), -1));
m_List.AddString(XFormatNumber(_T("1000000000"), -1));
m_List.AddString(XFormatNumber(_T("1000.0"), -1));
m_List.AddString(XFormatNumber(_T("1000.00"), -1));
m_List.AddString(XFormatNumber(_T("1000.000"), -1));
m_List.AddString(XFormatNumber(_T("1000.0000"), -1));
m_List.AddString(XFormatNumber(_T("1000.00000"), 1));

XFormatNumber Screenshot


This software is released into the public domain. You are free to use it in any way you like. If you modify it or extend it, please to consider posting new code here for everyone to share. This software is provided "as is" with no expressed or implied warranty. I accept no liability for any damage or loss of business that this software may cause.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Hans Dietrich
Software Developer (Senior) Hans Dietrich Software
United States United States
I attended St. Michael's College of the University of Toronto, with the intention of becoming a priest. A friend in the University's Computer Science Department got me interested in programming, and I have been hooked ever since.

Recently, I have moved to Los Angeles where I am doing consulting and development work.

For consulting and custom software development, please see

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Comments and Discussions

GeneralPerformance Improvement Pin
Gautam Jain26-Oct-07 4:32
memberGautam Jain26-Oct-07 4:32 
Thanks for the great code.

Imagine, if a program needs to format thousands of numbers, the XFormatNumber will get call GetLocaleInfo and fill in NUMBERFMT each time a number is formatted.

NUMBERFMT can be made static or global so that we don't GetLocaleInfo every time.

Gautam Jain

AnswerRe: Performance Improvement Pin
Hans Dietrich20-Apr-11 1:00
mentorHans Dietrich20-Apr-11 1:00 
Generaladded default value Pin
breakpoint3-May-06 17:21
memberbreakpoint3-May-06 17:21 
AnswerRe: added default value Pin
Hans Dietrich20-Apr-11 0:59
mentorHans Dietrich20-Apr-11 0:59 
GeneralSome comments Pin
Victor Boctor5-Dec-02 2:01
memberVictor Boctor5-Dec-02 2:01 
AnswerRe: Some comments Pin
Hans Dietrich20-Apr-11 0:59
mentorHans Dietrich20-Apr-11 0:59 
Generalfractional digits are limited to 9 Pin
C++ Hacker1-Jul-02 23:09
memberC++ Hacker1-Jul-02 23:09 
AnswerRe: fractional digits are limited to 9 Pin
Hans Dietrich20-Apr-11 0:58
mentorHans Dietrich20-Apr-11 0:58 

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