# include & ltiomanip & gt// Don't forget to include this header file.
Use namespace std
int main()
{
int a；
Cout < < "Enter a:";
CIN & gt； & gta；
cout & lt& lt" dec:" & lt； & ltdec & lt& lta & lt& ltendl？ //Output integers in decimal form
cout & lt& lt" hex:" & lt； & lt hexadecimal & lt& lta<& ltendl? //Output the integer a in hexadecimal form.
cout & lt& lt" oct:" & lt； & ltset base(8)& lt； & lta & lt& ltendl？ //Output the integer a in octal form?
Char *pt= "China"; ? //pt points to the string "China"?
cout & lt& ltsetw( 10)& lt； & ltpt & lt& ltendl？ //Specify the domain width as, and output the string?
cout & lt& ltset fill(' * ')& lt； & ltsetw( 10)& lt； & ltpt & lt& ltendl？ //Specify the field width, output the string, and fill the spaces with' *'?
Bipi = 22.0/7.0; ? //Calculate the value of pi?
//Output in exponential form, with 8 decimal places?
cout & lt& ltsetios flags(IOs::scientific)& lt； < set accuracy (8); ?
cout & lt& lt" pi = " & lt& ltpi & lt& ltendl？ //output pi value?
cout & lt& lt" pi = " & lt& ltsetprecision(4)& ltpi & lt& ltendl？ //Change to decimal places?
cout & lt& lt" pi = " & lt& ltsetios flags(IOs::fixed)& lt； & ltpi & lt& ltendl？ //Output in decimal form instead?
Returns 0;
}
Extended data
# Contains? & ltcstdio & gt//? In C and some ancient C++, it is STDIO. H. The new standard is to make a standard library.
//? The header file of is different from the user header file, so it is recommended not to use the extension.
//? For the original C library, C should be added in front of the header file name without using the extension.
Class? My outflow
{
Public:
const？ My outflow & Operator? & lt& lt？ (int？ value)const； //Overloading of integer variables
const？ My outflow & Operator? & lt& lt？ (char*？ str)const； //Overloading of string type
};
const？ My outflow & My outbound:: operator? & lt& lt(int？ Value) constant
{
Printf("%d ",value);
return*？ This; //Pay attention to this return. ...
}
const？ My outflow & My outbound:: operator? & lt& lt(char*？ Str) constant
{
printf("%s "，str)；
return*？ This; //Again, please pay attention here. ...
}
My outflow? Myout//myout, a global object that can serve us anytime and anywhere.
int？ Master ()
{
int？ A=2003;
char*？ MyStr= "Hello, world!" ;
I'm going out? & lt& lt？ myStr？ & lt& lt？ ”\ n”；
Return? 0;
}
References:
Baidu encyclopedia counting function