Print a number with comma delimited

Posted on 2006-07-02
Last Modified: 2012-06-27
I want to use printf to print out a number, say 4325932032, with comma delimited in thousands, that is, 4,325,932,032.

There is a way on an online faq telling us to use locale or a code snippet. We just wonder if there is a more reliable and convinient way to do so?
Question by:chcw
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LVL 22

Expert Comment

ID: 17035682
following function accepts in form of long integer and returns comma delimited character array

const char * ConvertCD(long v)
  static char   buf[16];
  static char   buf2[16];
  int           i;
  int           j;
  int           k;

  if (v >= 0)
    sprintf (buf, "%d", v);
    sprintf (buf, "%d", -v);
  if ((k = i = strlen (buf)) == 0)
    return buf;
  i = (i-1) / 3;
  for (j = 0; j < i; j++)
    { sprintf (buf2, "%.*s,%s", k - 3*(j+1), buf, buf + k - 3*(j+1));
    strcpy (buf, buf2);
  if (v < 0)
    sprintf (buf2, "-%s", buf);
    return buf2;
    return buf;


Expert Comment

ID: 17041636
Hi there,

I would take the number apart by powers of ten, i.e. 10, 100, 1000
but only look at powers dividable by 3, i.e. 1,1000, 1000000, ...

const char *ConvertCD(long Num)
bool IsNeg = (Num < 0);
char strNum[32]={""};      //** stores the result
long p(1), Frac;            //** Frac stores one three digits fraction of number
char buf[4];            //** temp. buffer for _itoa()

Num = abs(Num);                           // work on positive values
strcat(strNum, Num < 0 ? "-": "+");   // prefix sign
while (p)
      p      = 3*((int)log10(Num)/3);
      Frac  =  Num/pow(10,p);                           // contains 3-digit number (* 10^9, 10^6, 10^3, 10^0)
      Num -= Frac*pow(10,p);                          

      strcat(strNum, _itoa(Frac, buf, 10));      // this is not ansi .. maybe use sprinf(buf, "%i,", Frac);
      if (p>0) strcat(strNum, ",");
return strNum;
LVL 44

Expert Comment

ID: 17042128
There is an API function that will do that - GetNumberFormat

The GetNumberFormat function formats a number string as a number string customized for a specified locale.

int GetNumberFormat(
  LCID Locale,                // locale
  DWORD dwFlags,              // options
  LPCTSTR lpValue,            // input number string
  CONST NUMBERFMT *lpFormat,  // formatting information
  LPTSTR lpNumberStr,         // output buffer
  int cchNumber               // size of output buffer

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Expert Comment

ID: 17042136
LVL 44

Expert Comment

ID: 17042169

Author Comment

ID: 17047787
hi, AndyAinscow,

Can you provide a sample of usage? I cannot find one in MSDN.
LVL 44

Accepted Solution

AndyAinscow earned 500 total points
ID: 17048543
LVL 44

Expert Comment

ID: 17208198
My suggestion uses a standard windows function to do what was requested.

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