The use of setiosflags () in C ++, and the use of setiosflags in C ++

The use of setiosflags () in C ++, and the use of setiosflags in C ++

Cout <setiosflags (ios: fixed) <setiosflags (ios: right) <setprecision (2 );

Setiosflags is the C ++ operator included in the namespace iomanip. The operator is executed by a specified parameter.

 

Actions in the region;

 

Iso: fixed is one of the parameters of the setiosflags operator. The action specified by this parameter represents a floating point with a decimal point.

 

Number, and move the number to the right of the decimal point as much as possible within the allowed precision range;

 

Iso: right is also a setiosflags parameter, which specifies the right-aligned output in the specified area;

 

Setprecision is also a C ++ operator included in the namespace iomanip. This operator is used to set floating point numbers;

 

Setprecision (2) indicates the precision of the decimal point output, that is, the number of digits on the right of the decimal point is 2.

 

Cout <setiosflags (ios: fixed) <setiosflags (ios: right) <setprecision (2 );

 

The combination means to output a floating point number of two digits after the right-aligned decimal point.

 

 

You can use setprecision (n) to control the number of floating point numbers displayed in the output stream. The default value of C ++ is 6.

If setprecision (n) is used with setiosflags (ios: fixed), you can control the number of digits on the right of the decimal point.

Setiosflags (ios: fixed) is a real number expressed by a fixed point.

Supplement:

 

Q: What is the role of cout. setf () and cout. precision () in C ++?

 

A:

 

These two are format-controlled ~ In the ostream member functions, you can also use the output stream operator to control them, all of which are the same ~ For more information, see ~

 

Cout. setf is the same as setiosflags, and cout. precision is the same as setprecision ~

 

# Include <iomanip>

Here, iomanip has many functions:

This mainly applies to some operations such as cin and cout, such as setfill, setw, setbase, and setprecision. It is an I/O flow control header.

File, just like the formatted output in C. The following are some common control functions:

The base number of dec is 10, which is equivalent to "% d"

The base number of hex is 16, which is equivalent to "% X"

The base number of oct is 8, which is equivalent to "% o"

Setfill (c) is set to c

Setprecision (n) is set to show n decimal places

Setw (n): Set the domain width to n characters.

This control operator ensures that the output width is n. For example:

Cout <setw (3) <1 <setw (3) <10 <setw (3) <100; the output result is

1 10100 (right-aligned by default) setw (3) does not work when the output length is greater than 3 (<1000.

Setioflags (ios: fixed) fixed floating point display

Setioflags (ios: scientific) index Representation

Setiosflags (ios: left) left alignment

Setiosflags (ios: right) right-aligned

Setiosflags (ios: skipws ignore leading Blank

Setiosflags (ios: uppercase) hexadecimal number uppercase output

Setiosflags (ios: lowercase) hexadecimal lowercase output

Setiosflags (ios: showpoint) Forcibly displays the decimal point

Setiosflags (ios: showpos) force display symbol

Example:

# Include <iostream>

# Include <iomanip>

Using namespace std;

Int main ()

{

Cout <12345.0 <endl; // output "12345"

Cout <setiosflags (ios: fixed) <setprecision (3) <1.2345 <endl; output "1.235"

Cout <setiosflags (ios: scientific) <12345.0 <endl; // output "1.234500e +

 

004"

Cout <setprecision (3) <12345.0 <endl; // output "1.235e + 004"

Return 0;

}