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Re: Format 1234567.89 as 1,234,567.89 [message #41380 is a reply to message #41378]

Mon, 09 December 2013 04:49

Lance
Messages: 527
Registered: March 2007

Contributor

Which leads us to this question: how to write a customized formatter? The designers of U++ have actually provided quite wisely-designed way to expand the Format() functionality, even though it's not very well documented or demonstrated. You need to read the relevant library codes to understand it.

Instead of tolerating inconsistent/incorrect behavior and wait for somebody to fix the library, we can create our own customized Formatter and register it with the Core Formatting system.

Let's say, I want to create a MoneyFormatter to format numbers to certain decimal points and with thousand separator. And I have chosen 'm' as the format id. To keep it simple and stupid, we will allow specifying number of decimal points only. Here is some example of using the 'm' format id：
%m, format to 2 decimal points (default value);
%5m, format to 5 decimal points (padding with trailing 0s if needed)

Here is the required code, which can all be in the same cpp file, no declaration in any header file is needed.

static void sRegisterFormatters()
{
	ONCELOCK {
		RegisterNumberFormatter("m",  MoneyFormatter);
	}
}

INITBLOCK {
	sRegisterFormatters();
}
String Format(double number, unsigned decimal, const char * zeroAs=NULL);

String MoneyFormatter(const Formatting& f)
{
	if(IsNull(f.arg))
		return String();
	double value = f.arg;
	const char *s = f.format;
	int digits = 2;
	if(IsDigit(*s) || *s == '-' && IsDigit(s[1])) {
		digits = (int)strtol(s, NULL, 10);
		while(IsDigit(*++s))
			;
	}
	return Format(value, digits);
}

String Format(double number, unsigned decimal, const char * zeroAs)
{
	unsigned long long ipart,fract,mult=1ULL;
	String s;
	char buff[20];
	bool sign=number<0;

	if(IsNull(number))
		number=0.;

	if(number<-1e10 || number>1e10)
		return String("ERROR");

	if(sign)
		number=-number;

	double f=.5;

	for(unsigned i=0; i<decimal; i++){
		mult*=10;
		f/=10.;
	}
	number+=f;
	ipart=(unsigned long long)number;
	fract=(unsigned long long)((number-ipart)*mult);
	if(ipart==0uLL && fract==0uLL && zeroAs!=NULL)
		return s<<zeroAs;

	if(decimal>0)
		s<<fract;
	
	if((unsigned)s.GetLength()<decimal)
		s=String('0', decimal-s.GetLength()).Cat()<<s;

	if(decimal>0)
		s='.'+s;
	if(ipart==0)
		s="0"+s;
	while(ipart)
	{
		int j=ipart%1000;
		ipart /=1000;
		if(ipart)
		{
			sprintf(buff,",%03d", j);
		}else{
			sprintf(buff, "%d", j);
		}
		s=buff+s;
	}
	if(sign)
		s="-"+s;
	return s;
}

[Updated on: Mon, 09 December 2013 05:15]

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