Decimal point Output precision control problem

decimal point output precision control problem

SETF () is a function that appends the label word, and flags () is the label word

Fixed flag is to display floating-point numbers in fixed-point form

When there is a fixed mark, indicating that the data according to a certain number of digits output, or remove the fixed mark, the data in situ output---that is the number of the last 0 does not show

Therefore, there are two things to use:

(1) in-situ output, the fixed sign should be removed: cout. UNSETF (ios::fixed)

If 0.1 will output 0.1

(2) Set the number of output digits after the decimal point

A two-step:

The first step---------set the positioning output cout. SETF (ios::fixed)

The second step---------set the output precision cout. Precision (4)

As the following program:

#include <iostream.h>
#include <iomanip.h>
void Main (void)
{
COUT.SETF (ios::fixed);
Cout<<setprecision (2) << (float) 0.1<<endl;//output 0.10
COUT.UNSETF (ios::fixed);
Cout<<setprecision (2) << (float) 0.1<<endl; Output 0.1
}

fout<<rs<< '/t ' << '/t ' <<dr_mean<< ' (";

FOUT.SETF (ios::fixed);

fout<<dr_sd<< ")" <<endl;

FOUT.UNSETF (ios::fixed);

fout<< '/t ' << '/t ' <<mature_mean<< ' (";

FOUT.SETF (ios::fixed);
Fout.precision (4);

fout<<mature_sd<< ")" <<endl;

FOUT.UNSETF (ios::fixed);

fout<< '/t ' << '/t ' <<cost_mean<< ' (";

FOUT.SETF (ios::fixed);
Fout.precision (6);

fout<<cost_sd<< ")" <<endl;

FOUT.UNSETF (ios::fixed);

The output results are as follows:

0.998836---in situ (0.000000)---six-bit
2746.2---in situ (99.7445)--four-bit
3.152--in situ (0.015522)--six-bit

Other references are as follows:

* * about the format of floating-point numbers * *
#include <iostream.h>
void Main ()
{
float f=2.0/3.0,f1=0.000000001,f2=-9.9;
cout<<f<< ' <<f1<< ' <<f2<<endl; Normal output
COUT.SETF (Ios::showpos); Force Plus + before positive number
cout<<f<< ' <<f1<< ' <<f2<<endl;
COUT.UNSETF (Ios::showpos); Remove positive number before Plus +
COUT.SETF (Ios::showpoint); Force display of invalid 0 after decimal point
cout<<f<< ' <<f1<< ' <<f2<<endl;
COUT.UNSETF (Ios::showpoint); Suppresses invalid 0 after the decimal point is displayed
COUT.SETF (ios::scientific); Scientific method of Accounting
cout<<f<< ' <<f1<< ' <<f2<<endl;
COUT.UNSETF (ios::scientific); Elimination of scientific notation
COUT.SETF (ios::fixed); Display by point output
cout<<f<< ' <<f1<< ' <<f2<<endl;
COUT.UNSETF (ios::fixed); Cancel the dot output display
Cout.precision (18); Accuracy is 18, normal is 6
cout<<f<< ' <<f1<< ' <<f2<<endl;
Cout.precision (6); Precision restored to 6
}
Manipulation operator:
* * about the format of floating-point numbers * *
#include <iomanip.h>
void Main ()
{
float f=2.0/3.0,f1=0.000000001,f2=-9.9;
cout<<f<< ' <<f1<< ' <<f2<<endl; Normal output
Cout<<setiosflags (Ios::showpos); Force Plus + before positive number
cout<<f<< ' <<f1<< ' <<f2<<endl;
Cout<<resetiosflags (Ios::showpos); Remove positive number before Plus +
Cout<<setiosflags (Ios::showpoint); Force display of invalid 0 after decimal point
cout<<f<< ' <<f1<< ' <<f2<<endl;
Cout<<resetiosflags (Ios::showpoint); Suppresses invalid 0 after the decimal point is displayed
Cout<<setiosflags (ios::scientific); Scientific method of Accounting
cout<<f<< ' <<f1<< ' <<f2<<endl;
Cout<<resetiosflags (ios::scientific); Elimination of scientific notation
Cout<<setiosflags (ios::fixed); Display by point output
cout<<f<< ' <<f1<< ' <<f2<<endl;
Cout<<resetiosflags (ios::fixed); Cancel the dot output display
Cout<<setprecision (18); Accuracy is 18, normal is 6
cout<<f<< ' <<f1<< ' <<f2<<endl;
Cout<<setprecision (6); Precision restored to 6
}

Resources:

Http://zhidao.baidu.com/question/9029358.html

Http://zhidao.baidu.com/question/77286598.html

Http://bbs.bccn.net/thread-150172-1-1.html