operator>>(std::basic_istream)
运算符>>%28std：：basic[医]iStream%29
| template< class CharT, class Traits > basic_istream | (1) | |
|---|---|---|
| template< class CharT, class Traits> basic_istream<CharT,Traits>& operator>>( basic_istream<CharT,Traits>& st, CharT* s template< class Traits > basic_istream<char,Traits>& operator>>( basic_istream<char,Traits>& st, signed char* s template< class Traits > basic_istream<char,Traits>& operator>>( basic_istream<char,Traits>& st, unsigned char* s | (2) | |
| | (3) | |
| template< class CharT, class Traits, class T > basic_istream<CharT,Traits>& operator>>( basic_istream<CharT,Traits>&& st, T& value | (since C++11) (until C++17) | |
| template< class CharT, class Traits, class T > basic_istream<CharT,Traits>& operator>>( basic_istream<CharT,Traits>&& st, T&& value | (since C++17) |
执行字符输入操作。
1%29表现为FormattedInputFunction.在构造和检查哨兵对象之后，该对象可能跳过前导空格，提取字符并将其存储到ch如果没有字符可用，则设置failbit%28eofbit设置为FormattedInputFunction29%。
2%29表现为FormattedInputFunction.在构造和检查哨兵对象之后，该对象可能跳过前导空格，然后提取连续字符并将它们存储在字符数组的连续位置，该字符数组的第一个元素由s.如果符合下列条件之一，则停止提取：
- 由ctype<CharT>小面%29被找到。未提取空白字符。
st.width() - 1字符提取
- 文件的结尾发生在输入序列%28中，这也是
eofbit%29
在这两种情况下，都会增加一个空字符值。CharT()存储在输出的末尾。如果没有提取字符，则设置failbit%28空字符仍被写入输出%29中的第一个位置。最后，呼叫st.width(0)取消…的影响std::setw如果有的话。3%29。
| Calls the appropriate extraction operator, given an rvalue reference to an input stream object (equivalent to st >> value). | (since C++11)(until C++17) |
|---|---|
| Calls the appropriate extraction operator, given an rvalue reference to an input stream object (equivalent to st >> std::forward<T>(value)). This function does not participate in overload resolution unless the expression st >> std::forward<T>(value) is well-formed. | (since C++17) |
注记
提取流中最后一个字符的单个字符没有设置。eofbit这与其他格式化的输入函数不同，例如用operator>>，但此行为与std::scanf带着"%c"格式说明符。
参数
| st | - | input stream to extract the data from |
|---|---|---|
| ch | - | reference to a character to store the extracted character to |
| s | - | pointer to a character string to store the extracted characters to |
返回值
st...
例
二次
#include <iostream>
#include <iomanip>
#include <sstream>
int main()
{
std::string input = "n greetings";
std::istringstream stream(input
char c;
const int MAX = 6;
char cstr[MAX];
stream >> c >> std::setw(MAX) >> cstr;
std::cout << "c = " << c << '\n'
<< "cstr = " << cstr << '\n';
double f;
std::istringstream("1.23") >> f; // rvalue stream extraction
std::cout << "f = " << f << '\n';
}
二次
产出：
二次
c = n
cstr = greet
f = 1.23
二次
另见
| operator>> | extracts formatted data (public member function) |
|---|
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