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c++stringdoubledecimal
thahgr
thahgr

Reputation: 795

Convert double to string keeping high precision of the digits, C++

I have been trying to convert a double into string without the C++11 (ToString) but it only accepts the number of decimals to be 5 as default. How can I change that?

The command is:

    string a = static_cast<ostringstream*>( &(ostringstream()<<digits) )->str();

but it keeps 5 decimals while I want to create a string which has all the decimals (e.g. 100) I know that, that many decimals dont matter. This is one point of the exercise I was doing.

Any suggestions?

Thank you very much for your time Cheers!

Upvotes: 1

Views: 3119

Answers (2)

thahgr
thahgr

Reputation: 795

This worked for me finally

      digits = 1.12345123451234;
      char buff[100];
      sprintf(buff, "%1.14f", digits);
      string a(buff);

Thanks for checking it in any case

Cheers

Upvotes: 0

Johan
Johan

Reputation: 3778

Use IO manipulators setprecision here on std::cout but works on stringstream:

// setprecision example from cplusplus.com
#include <iostream>     // std::cout, std::fixed
#include <iomanip>      // std::setprecision

int main () {
  double f =3.14159;
  std::cout << std::fixed << std::setprecision(9) << f << '\n';
  return 0;
}

By the way, no double will have 100 meaningfull digit, it's 15 or 17, I forgot exactly how many.

EDIT: I forgot, if you can use C++11... You can (and should) use to_string

#include <string>

// ....    
std::string f_str = std::to_string(f);

Upvotes: 5

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