C++ basic_istream 库 - operator>>

描述

应用于输入流的这种运算符 (>>) 称为提取运算符。

声明

以下是 std::basic_istream::operator>> 的声明。

C++98

basic_istream& operator>> (bool& val);
basic_istream& operator>> (short& val);
basic_istream& operator>> (unsigned short& val);
basic_istream& operator>> (int& val);
basic_istream& operator>> (unsigned int& val);
basic_istream& operator>> (long& val);
basic_istream& operator>> (unsigned long& val);
basic_istream& operator>> (float& val);
basic_istream& operator>> (double& val);
basic_istream& operator>> (long double& val);
basic_istream& operator>> (void*& val);
stream buffers (2)	
basic_istream& operator>> (basic_streambuf<char_type,traits_type>* sb );
manipulators (3)	
basic_istream& operator>> (basic_istream& (*pf)(basic_istream&));
basic_istream& operator>> (
  basic_ios<char_type,traits_type>& (*pf)(basic_ios<char_type,traits_type>&));
basic_istream& operator>> (ios_base& (*pf)(ios_base&));

C++11

basic_istream& operator>> (bool& val);
basic_istream& operator>> (short& val);
basic_istream& operator>> (unsigned short& val);
basic_istream& operator>> (int& val);
basic_istream& operator>> (unsigned int& val);
basic_istream& operator>> (long& val);
basic_istream& operator>> (unsigned long& val);
basic_istream& operator>> (long long& val);
basic_istream& operator>> (unsigned long long& val);
basic_istream& operator>> (float& val);
basic_istream& operator>> (double& val);
basic_istream& operator>> (long double& val);
basic_istream& operator>> (void*& val);
stream buffers (2)	
basic_istream& operator>> (basic_streambuf<char_type,traits_type>* sb );
manipulators (3)	
basic_istream& operator>> (basic_istream& (*pf)(basic_istream&));
basic_istream& operator>> (
  basic_ios<char_type,traits_type>& (*pf)(basic_ios<char_type,traits_type>&));
basic_istream& operator>> (ios_base& (*pf)(ios_base&));

参数

• val − 它是存储提取的字符所代表的值的对象。

• sb − 指向 basic_streambuf 对象的指针，在其受控输出序列上复制字符。

• pf − 接受并返回流对象的函数。 它通常是一个操纵器功能。

返回值

返回 basic_istream 对象 (*this)。

异常

修改 val 或 sb 指向的对象并修改流对象。

异常与安全

Basic guarantee − 如果抛出异常，则对象处于有效状态。

示例

在下面的 std::basic_istream::operator>> 示例中

#include <iostream>     

int main () {
   int n;

   std::cout << "Enter a number: ";
   std::cin >> n;
   std::cout << "You have entered: " << n << '\n';

   std::cout << "Enter a hexadecimal number: ";
   std::cin >> std::hex >> n;         
   std::cout << "Its decimal equivalent is: " << n << '\n';

   return 0;
}

让我们编译并运行上面的程序，这将产生以下结果 −

Enter a number: 1
You have entered: 1
Enter a hexadecimal number: 5E
Its decimal equivalent is: 94

❮ C++ 标准库 - <istream>