Parse the formatted output of the C ++ floating point number

C ++ format the output floating point number
Copy codeThe Code is as follows: # include <iostream>
Using std: cout;
Using std: endl;
Using std: fixed;
Using std: scientific;
Int main ()
{
Double x = 0.001234567;
Double y = 1.946e9;
Cout <"Displayed in default format:" <endl <x <'/t' <y <endl;
Cout <"/nDisplayed in scientific format:" <endl <scientific <x <'/t' <y <endl;
Cout <"/nDisplayed in fixed format:" <endl <fixed <x <'/t' <y <endl;
Return 0;
}

Displayed in default format:
0.00123457 1.946e + 009
Displayed in scientific format:
1.234567e-003 1.946000e + 009
Displayed in fixed format:
0.001235 1946000000.000000Copy codeThe Code is as follows: # include <iostream. h>
Main (void)
{
Float a = 100100.0, B = 0.08;
Cout. setf (ios: right | ios: scientific | ios: showpoint );
Cout. width (20 );
Cout <(-a * B );

Return 0;
}

-8.008000e + 003Copy codeThe Code is as follows: # include <iostream>
# Include <iomanip>
# Include <limits>
Using std: cout;
Using std: endl;
Using std: setprecision;
Using std: numeric_limits;
Int main (){
Const double pi = 3.14;
Cout <endl;
For (double radius =. 2; radius <= 3.0; radius + =. 2)
Cout <"radius ="
<Setprecision (numeric_limits <double>: digits10 + 1)
<Std: scientific <radius <"area ="
<Std: setw (10) <setprecision (6) <std: fixed <pi * radius * radi
Us <endl;
Return 0;
}

Radius = 2.20.000000000001e-001 area = 0.125600
Radius = 4.20.000000000002e-001 area = 0.502400
Radius = 6.20.000000000009e-001 area = 1.130400
Radius = 8.20.000000000004e-001 area = 2.009600
Radius = 1.20.00000000e + 000 area = 3.140000
Radius = 1.200000000000e + 000 area = 4.521600
Radius = 1.39999999999999e + 000 area = 6.154400
Radius = 1.5999999999999999e + 000 area = 8.038400
Radius = 1.7999999999999998e + 000 area = 10.173600
Radius = 1.9999999999999998e + 000 area = 12.560000
Radius = 2.tms999999999997e + 000 area = 15.197600
Radius = 2.39999999999999e + 000 area = 18.086400
Radius = 2.6000000000000001e + 000 area = 21.226400
Radius = 2.8000000000000003e + 000 area = 24.617600Copy codeThe Code is as follows: # include <iostream>
# Include <iomanip>
# Include <string>
Using namespace std;
Int main (){
Ios_base: fmtflags flags = cout. flags ();
Double pi = 3.14285714;
Cout <"pi =" <setprecision (5) <pi <'/N ';
Cout. flags (flags );
}

Pi = 1, 3.1429Copy codeThe Code is as follows: # include <iostream>
# Include <iomanip>
# Include <math. h>
Using namespace std;
Int main ()
{
Double root2 = sqrt (2.0 );
Int places;
Cout <setiosflags (ios: fixed)
<"Square root of 2 with precisions 0-9./n"
<"Precision set by"
<"Precision member function:" <endl;
For (places = 0; places <= 9; places ++ ){
Cout. precision (places );
Cout <root2 <'/N ';
}
Cout <"/nPrecision set by"
<"Setprecision manipulator:/n ";
For (places = 0; places <= 9; places ++)
Cout <setprecision (places) <root2 <'/N ';
Return 0;
}