How to use custom thousand separator and decimal character with std::stringstream?

Asked Mar 16 '18 at 11:16

Active Mar 16 '18 at 12:52

Viewed 637 times

I have a string that represents a floating point number, like "1000.34". I want to apply some thousand and decimal separator rules to that string so that, for example, it turns into "1,000.34".

I tried to do the following:

ss.imbue(std::locale(ss.getloc(), new mySeparator));

struct mySeparator : std::numpunct<char> {
    char do_decimal_point() const {
      return '.';
    }
    char do_thousands_sep() const {
      return ',';
    }
    std::string do_grouping() const {
      return "\000"; // Groups of 3
    }
  };

But this only works when it's a number, not a string:

double number = 1000.34;
ss << number;

How can I do the same when what I have is a string representing the number? Is there an alternative approach?

asked Mar 16 '18 at 11:16

Juan Herrero Diaz

1

Parse it using `std::istringstream`, then send it to the output as a `float` or `double`. – Thomas Mar 16 '18 at 11:18
What would happen if I output "1000.00"? I want to keep the ".00" in the `double` variable. – Juan Herrero Diaz Mar 16 '18 at 11:27
Possible duplicate of [How to parse a string to an int in C++?](https://stackoverflow.com/questions/194465/how-to-parse-a-string-to-an-int-in-c) – Smit Ycyken Mar 16 '18 at 12:08
Have a look at #What not to do: do not use stringstream for this. – Smit Ycyken Mar 16 '18 at 12:09

How to use custom thousand separator and decimal character with std::stringstream?

0 Answers0