Setting decimal precision in fstream

How do you increase it from six decimal places? A programmer's reference book I have speaks of a precision(int p); function, but MSVC++6 doesn't seem to support it.

Code:

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#include <iostream>
#include <iomanip>

int main()
{
  double d = 11.12345678901;
  std::cout.setf(std::ios::showpoint | std::ios::fixed);
  std::cout <<std::setprecision(11) <<d <<std::endl;
}

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