Extra Digits of Precision

[emaghero]

Does anyone know how to ouput extra digits of precision in C++?

I am using Microsft Visual Studio to write my C++ code and I want to get at least 20 - 30 digits of precision on screen and for outputting to a txt file.

At the moment I use printf("%16.24lf\n", number);

I would like to know if there is a C++ equivalent?

emaghero.

[ssharish]

Well there is member function with the cout object called a precision which actually set or gets the precision. The following shows u on how to use it

cout.precision(5); // Sets the precsion to 5
 

some sample code using the precision

#include <iostream>
#include <cstdlib>
 
using namespace std;
 
int _tmain(int argc, _TCHAR* argv[])
{
    double value = 1.23652458759653;
 
    cout.precision(20);
    cout<<"The double printed with 5 precision -> "<<value<<endl;
 
    cin.get();
    return 0;
}
 
/*my output
The double printed with 5 precision -> 1.2365245875965301
*/
 

ssharish

[emaghero]

That looks like it will do the business.

Thanks very much

emaghero

[vninja]

if you want to be lazier you could just use
setprecition(N)
before the value eg

cout << "the value " << setprecition(N) << value;

use N as a global const or as a var to make it easier on yourself

[emaghero]

if you want to be lazier you could just use
setprecition(N)
before the value eg

cout << "the value " << setprecition(N) << value;

use N as a global const or as a var to make it easier on yourself

Thanks very much. I think I like that one better.

[Banfa]

I am using Microsft Visual Studio to write my C++ code and I want to get at least 20 - 30 digits of precision on screen and for outputting to a txt file.

There is not much point specifying 20-30 bit precision when the double type (which is the most precise type that MSVC++ supports) only holds 15 bits of precision. You will just end up with 5 - 15 0s at the end of your number.