C++ format int numbers to separate thousands with a dot - c++

Question

I'm working on Eclipse, on Fedora. I want to make a number more understandable using a dot to separate the thousands. This number is an integer Value that can be 0<Value<99.999
So... if Value = 1000 it shows 1000 and what I want is to show 1.000 (note the dot). The code I need to change is the next one:
char str[12];
sprintf(str, "%d", (int)(Value));
m_Text.SetText(str);
And what I thought is to do something like:
if (Value > 999)
{
int RightPart = (int)Value % 1000;
int LeftPart = Val/1000 ;
}
And then append in a string LeftPart + "." + RightPart so if Value = 1563 it will be 1+.+563 which is 1.563
My problem is that it's very ugly to do this and I was wondering if there were a better way of doing it. I've searched on google and found imbueand localebut they are only for cout. I've see too some posts like this and this but this doesn't help me with my problem.
Thank you.
NOTE: I want to remark that I DON'T WANT to change the output format. I want to change the int I receive so I can have the dots in the str var with which I will work later.
NOTE 2: Basically the code has to: receive an integer (Value), and send it like a string to setText(). setText() will basically print it on the screen where and when it has to, and I want it to print 1.563 and not 1563 which is more difficult to read.

Answer 1

Use stringstream and same imbue technique for it.
For example:
struct dotted : std::numpunct<char> {
char do_thousands_sep() const { return '.'; } // separate with dots
std::string do_grouping() const { return "\3"; } // groups of 3 digits
static void imbue(std::ostream &os) {
os.imbue(std::locale(os.getloc(), new dotted));
}
};
and then:
std::stringstream ss;
dotted::imbue(ss);
ss << Value;
std::cout << ss.str();
Demo

Answer 2

#include <iomanip>
#include <locale>
#include <iostream>
#include <sstream>
using namespace std;
template<class T>
string format(T value)
{
stringstream ss;
ss.imbue(locale(""));
ss << fixed << value;
return ss.str();
}
int main(int argc, char argv[])
{
cout.imbue(locale(""));
cout << 1000000 << endl;
return 0;
}
Prints:
1.000.000
You should probably look at which locale is used when "" is passed and change it with a more appropriate one.
Or vice versa:
int str_to_nr(string str)
{
int val;
stringstream ss(str);
ss.imbue(locale(""));
ss >> val;
return val;
}
int main(int argc, char argv[])
{
cout << str_to_nr("1.000") << endl;
return 0;
}
Prints:
1000

Answer 3

#gandgandi's answer basically gives you a technique to print out the value with dots on demand using C++ streams.
sprintf (which is generally not safe to use, BTW) is a C library function. C does not provide a mechanism to alter the locale behavior in the same way C++ provides. In C, you will have to define the locale behavior with mechanisms/tools provided by your operating system and assign it a name. Then, you can use the C function setlocale to alter the locale in the program to the one you have created to get it to print how you want. However, this will only work on machines that have the locale you have created installed. It won't work on any other machine.
With only a little bit of work and almost no creative effort, you can just use the C++ solution already provided combined with a call to sprintf.
char str[12];
stringstream ss;
dotted::imbue(ss);
ss << Value;
sprintf(str, "%s", ss.str());
m_Text.SetText(str);
But, there is really no reason to use sprintf at all:
stringstream ss;
dotted::imbue(ss);
ss << Value;
m_Text.SetText(ss.str());