fig12_09.cpp

来自「《c＋＋大学教程》源码」· C++ 代码 · 共 57 行

// Fig. 12.9: fig12_09.cpp 
// Controlling precision of floating-point values.
#include <iostream>

using std::cout;
using std::cin;
using std::endl;
using std::fixed;

#include <iomanip>

using std::setprecision;

#include <cmath>  // sqrt prototype

int main()
{
   double root2 = sqrt( 2.0 ); // calculate square root of 2
   int places;

   cout << "Square root of 2 with precisions 0-9." << endl
        << "Precision set by ios_base member-function "
        << "precision:" << endl;

   cout << fixed; // use fixed precision

   // display square root using ios_base function precision
   for ( places = 0; places <= 9; places++ ) {
      cout.precision( places );
      cout << root2 << endl;
   }

   cout << "\nPrecision set by stream-manipulator " 
        << "setprecision:" << endl;

   // set precision for each digit, then display square root
   for ( places = 0; places <= 9; places++ )
      cout << setprecision( places ) << root2 << endl;

   return 0;

} // end main

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