C++ decimal output formatting

Question

i'm writing a double value to a file. The numeric value is written with a point as a decimal separator. I would like to use a comma. How i can do that?

Please post your code, without code to reference it's hard to make suggestions — Sam Post, Feb 09 '10 at 01:11

score 3 · Accepted Answer · answered Feb 09 '10 at 01:11

3

The usual way is to use a locale with the decimal separator set to the comma. If your machine is configured for that generally, you can probably just use the nameless locale for it:

std::cout.imbue(std::locale(""));
std::cout << 12345.67;

answered Feb 09 '10 at 01:11

Jerry Coffin

476,176
80
629
1,111

score 2 · Answer 2 · edited May 23 '17 at 11:47

2

You can find the answer in an earlier question This basically changes the locale used by the streams you are using.

edited May 23 '17 at 11:47

Community

1
1

answered Feb 09 '10 at 01:10

Michael Anderson

70,661
7
134
187

score -1 · Answer 3 · answered Feb 09 '10 at 01:10

I think in the library cmath

there is a function called modf which takes a float or double, and a pointer to an float or double, and returns an integer.

double intPart;
double fractPart;
fractPart = modf(doubleValue, &intPart);

So you pass in the double value, it returns the decimal part as an integer, and the integer value is stored in the pointer you passed in.

You could then write these to file however you want, with a comma in the middle or whatever, just write it as two separate numbers. float or double

C++ decimal output formatting

3 Answers3

Linked