C++之输入输出流

                     1 #include<iostream>
 2usingnamespace std;
 3//设置输出宽度  4int main()
 5 { char *s = "Hello";
 6    cout.fill( ‘*‘ ) ;    //设置填充符             7    cout.width( 10 ) ;    //设置输出宽度 8    cout.setf( ios :: left ) ;    //设置左对齐 9    cout << s << endl ;
10    cout.width( 15 ) ;    //设置输出宽度11    cout.setf( ios :: right, ios :: left ) ;    //消除左对齐标志位，设置右对齐    12    cout << s << endl ;
13 } 

                     1 #include<iostream>
 2usingnamespace std;
 3int main()
 4 { int a , b , c ;
 5    cout << "please input a in decimal: " ;
 6    cin >> dec >> a ;
 7//cin.setf( ios :: dec , ios :: basefield ) ;
 8//cin >> a ;    //十进制输入 910    cout << "please input b in hexadecimal: " ;    
11    cin >> hex >> b ;
12//cin.setf( ios :: hex , ios :: basefield ) ;
13//cin >> b ;     //十六进制输入1415    cout << "please input c in octal: " ;
16    cin >> oct >> c ;
17//cin.setf( ios :: oct , ios :: basefield ) ;
18//cin >> c ;     //八进制输入1920    cout << "Output in decimal :\n" ;
21    cout <<"a = "<<a<<" b = "<<b<<"  c = "<<c<<endl ;
22//cout.setf( ios :: dec, ios :: basefield );            //十进制输出
23//cout << "a = " << a << "  b = " << b << "  c = " << c << endl ;2425    cout <<hex<<"a = "<<a<<" b = "<<b<<" c = "<<c<<endl ;
26//cout.setf( ios :: hex , ios :: basefield ) ;        //十六进制输出27    cout << "Output in hexadecimal :\n" ;
28    cout << "a = " << a << "  b = " << b << "  c = " << c << endl ;
2930    cout <<oct<<"a = "<<a<<" b = "<<b<<" c = "<<c<<endl ;
3132//cout.setf( ios :: oct , ios :: basefield ) ;        //八进制输出
33//cout << "Output in octal :\n" ;34    cout << "a = " << a << "  b = " << b << "  c = " << c << endl ;
35 }

                     1 #include<iostream>
 2usingnamespace std;
 3int main()
 4 { double x = 22.0/7 ;
 5int i ;
 6    cout << "output in fixed :\n" ;
 7    cout.setf( ios::fixed | ios::showpos ) ;         // 定点输出，显示 + 8for( i=1; i<=5; i++ )
 9       { cout.precision( i ) ;  cout << x << endl ; }
10    cout << "output in scientific :\n" ;
11// 清除原有设置，科学示数法输出12    cout.setf(ios::scientific, ios::fixed|ios::showpos ) ;    
13for( i=1; i<=5; i++ )
14       { cout.precision(i) ;   cout << x*1e5 << endl ; }
15 }

11.iomanip的控制符

                         1
                        //
                         例11-7  整数的格式化输出
                         2 #include <iostream>
 3 #include <iomanip>
 4usingnamespace std ;
 5int main()
 6 { constint k = 618 ;
 7    cout << setw(10) << setfill(‘#‘) << setiosflags(ios::right) << k <<endl ;
 8    cout << setw(10) << setbase(8) << setfill(‘*‘)
 9            << resetiosflags(ios::right) << setiosflags(ios::left) << k << endl ;
10 }