C++/Data Type/double output

double: Formatting aligns columns, pads blank spaces with "0" character, and controls precision of answer.

<source lang="cpp">

1. include <iostream>
2. include <iomanip>
3. include <math.h>

using namespace std; main( ) {

double number,square,sqroot;
 
cout << "num\t" << "square\t\t" << "square root\n";
number=1.0;
cout.setf(ios::fixed);     
for(int i=1;i<16;i++) {
  square=number*number;    
  sqroot=sqrt(number);     
  cout.fill("0");             // fill blanks with zeros
  cout.width(2);              // column 2 characters wide
  cout.precision(0);          // no decimal place
  cout << number << "\t";
  cout.width(6);              // column 6 characters wide
  cout.precision(1);          // print 1 decimal place
  cout << square << "\t\t";
 
    cout.width(8);          // column 8 characters wide
  cout.precision(6);          // print 6 decimal places
  cout << sqroot << endl;
  number+=1.0;
}
return (0);

}

 </source>

Fixed format with precision of 7

<source lang="cpp">

1. include <iostream>
2. include <iomanip>

using namespace std; int main() {

 cout << "Default format: " << 123.123456789 << endl;
 cout << "Fixed format with precision of 7: ";
 cout << setprecision(7) << fixed << 123.123456789 << endl;
 return 0;

}

 </source>

Scientific format with precision of 7

<source lang="cpp">

1. include <iostream>
2. include <iomanip>

using namespace std; int main() {

 cout << "Default format: " << 123.123456789 << endl;
 cout << "Scientific format with precision of 7: ";
 cout << scientific << 123.123456789 << endl;
 return 0;

}

 </source>

Set fixed flag for double value

<source lang="cpp">

1. include <iostream>

using namespace std; int main() {

 int x = 100;
 double f = 98.6;
 double f2 = 123456.0;
 double f3 = 1234567.0;
 cout.setf(ios::fixed, ios::floatfield);
 cout << "After setting fixed flag:\n";
 cout << "f: " << f << "  f2: " << f2 << "  f3: " << f3 << "\n\n";
 return 0;

}

 </source>

Set scientific flag when outputing double

<source lang="cpp">

1. include <iostream>

using namespace std; int main() {

 int x = 100;
 double f = 98.6;
 double f2 = 123456.0;
 double f3 = 1234567.0;
 cout.setf(ios::scientific, ios::floatfield);
 cout << "After setting scientific flag:\n";
 cout << "f: " << f << "  f2: " << f2 << "  f3: " << f3 << endl;

 return 0;

}

 </source>

Set showpos flag for double

<source lang="cpp">

1. include <iostream>

using namespace std; int main() {

 int x = 100;
 double f = 98.6;
 double f2 = 123456.0;
 double f3 = 1234567.0;
 // Set the showpos flag.
 cout.setf(ios::showpos);
 cout << "Setting showpos flag.\n";
 cout << "f in default notation after setting showpos: " << f << "\n\n";
 return 0;

}

 </source>

Set the precision to 9

<source lang="cpp">

1. include <iostream>

using namespace std; int main() {

 double f = 123456.123456789;
 cout << "Using default numeric format.\n";
 cout << "f with default precision: " << f << "\n\n";
 cout << "Setting the precision to 9.\n";
 cout.precision(9);
 cout << "f with precision of 9: " << f << "\n\n";
 cout << "Switching to fixed-point format.\n";
 cout.setf(ios::fixed, ios::floatfield);
 cout << "f with precision of 9 in fixed-point: " << f << "\n\n";
 // Now, display two decimal places.
 cout << "Display two decimal places in all cases: ";
 cout.precision(2);
 cout << 12.456 << " " << 10.0 << " " << 19.1 << endl;
 return 0;

}

 </source>

Set the uppercase flag for double value

<source lang="cpp">

1. include <iostream>

using namespace std; int main() {

 int x = 100;
 double f = 98.6;
 double f2 = 123456.0;
 double f3 = 1234567.0;
 // Set the uppercase flag.
 cout << "Setting uppercase flag.\n";
 cout.setf(ios::uppercase);
 cout << "f3 with uppercase flag set: " << f3 << endl;
 return 0;

}

 </source>