C++: I/O流详解

一、输入流操作

1.read 无格式输入指定字节数

istream& read ( char* pch, int nCount );

istream& read ( unsigned char* puch, int nCount );

istream& read ( signed char* psch, int nCount );

2.get 从流中提取字符，包括空格

int get();

istream& get( char* pch, int nCount, char delim = '\n' );

istream& get( unsigned char* puch, int nCount, char delim = '\n' );

istream& get( signed char* psch, int nCount, char delim = '\n' );

istream& get( char& rch ); istream& get( unsigned char& ruch );

istream& get( signed char& rsch );

istream& get( streambuf& rsb, char delim = '\n' );

3.getline 从流中提取一行字符

istream& getline( char* pch, int nCount, char delim = '\n' );

istream& getline( unsigned char* puch, int nCount, char delim = '\n' );

istream& getline( signed char* psch, int nCount, char delim = '\n' );

4.ignore 提取并丢弃流中指定字符

istream& ignore( int nCount = 1, int delim = EOF );

5.peek 返回流中下一个字符，但不从流中删除

int peek();

6.gcount 统计最后输入的字符个数

int gcount() const;

7.eatwhite 忽略前导空格

void eatwhite();

8.seekg 移动输入流指针

istream& seekg( streampos pos );

istream& seekg( streamoff off, ios::seek_dir dir );

9.tellg 返回输入流中指定位置的指针值

streanpos tellg();

10.operator >> 提取运算符

basic_istream& operator>>( basic_istream& (*pf)(basic_istream&));

basic_istream& operator>>( basic_ios<E, T>& (*pf)(basic_ios<E, T>&));

basic_istream& operator>>( ios_base<E, T>& (*pf)(ios_base<E, T>&));

basic_istream& operator>>( basic_streambuf<E, T> *sb);

basic_istream& operator>>(bool& n);

basic_istream& operator>>(short& n);

basic_istream& operator>>(unsigned short& n);

basic_istream& operator>>(int& n);

basic_istream& operator>>(unsigned int& n);

basic_istream& operator>>(long& n);

basic_istream& operator>>(unsigned long& n);

basic_istream& operator>>(void *& n);

basic_istream& operator>>(float& n);

basic_istream& operator>>(double& n);

basic_istream& operator>>(long double& n);

例子：

 //用get函数从键盘输入字符
 void f1(){
     char c;
     cout<<"Enter first sentence followed by enter\n";
     while((c = cin.get())!='\n')
         cout.put(c);
     cout<<endl;

     cout<<"Enter second sentence followed by enter\n";
     while(cin.get(c)){
         if (c == '\n')
             break;
         cout.put(c);
     }
     cout<<endl;

     cout<<"Enter thired sentence followed by enter\n";
     char s[];
     cin.get(s, );
     cout<<s<<endl;
 }

输出：

二、输出流

1.put 无格式，插入一个字节

ostream& put(char ch);

2.write 从无格式，插入一字节序列

ostream& write( const char* pch, int nCount );

ostream& write( const unsigned char* puch, int nCount );

ostream& write( const signed char* psch, int nCount );

3.flush 刷新输出流

ostream& flush();

4.seekp 移动输出流指针

ostream& seekp( streampos pos );

ostream& seekp( streamoff off, ios::seek_dir dir );

5.tellp 返回输出流中指定位置的指针

streampos tellp();

6.operstor<< 插入运算符

basic_ostream& operator<<( basic_ostream& (*pf)(basic_ostream&));

basic_ostream& operator<<( basic_ios<E, T>& (*pf)(basic_ios<E, T>&));

basic_ostream& operator<<( ios_base<E, T>& (*pf)(ios_base<E, T>&));

basic_ostream& operator<<( basic_streambuf<E, T> *sb);

basic_ostream& operator<<(const char *s);

basic_ostream& operator<<(char c);

basic_ostream& operator<<(bool n);

basic_ostream& operator<<(short n);

basic_ostream& operator<<(unsigned short n);

basic_ostream& operator<<(int n);

basic_ostream& operator<<(unsigned int n);

basic_ostream& operator<<(long n);

basic_ostream& operator<<(unsigned long n);

basic_ostream& operator<<(float n);

basic_ostream& operator<<(double n);

basic_ostream& operator<<(long double n);

basic_ostream& operator<<(void *n);

例子：

 #include<iostream.h>
 void main()
 { cout << "Enter a sentence followed by Enter\n" ;
   char s[  ] ;
   cin.getline ( s,  ) ;
   cout.write(s, ) ;
   cout<<endl;
 }

输出：

三、流错误状态