std::basic_istream::sentry
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< cpp | io | basic istream
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| 在头文件 <istream> 中定义
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| template< class CharT, class Traits = std::char_traits<CharT>> class std::basic_istream<CharT, Traits>::sentry; |
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An object of class basic_istream::sentry is constructed in local scope at the beginning of each member function of std::basic_istream that performs input (both formatted and unformatted). Its constructor prepares the input stream: checks if the stream is already in a failed state, flushes the tie()'d output streams, skips leading whitespace if skipws flag is set, and performs other implementation-defined tasks if necessary. All cleanup, if necessary, is performed in the destructor, so that it is guaranteed to happen if exceptions are thrown during input.
目录 |
[编辑] 会员类型
traits_type
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Traits |
[编辑] 成员函数
| 构建哨兵object. All的准备工作都在这里完成 原文： constructs the sentry object. All the preparation tasks are done here （公共成员函数） | |
| finalizes the stream object after formatted input or after exception, if necessary （公共成员函数） | |
| operator= [删除]</div></div>
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无法复制转让 （公共成员函数） |
| 如果编写的流对象的检查是成功的 原文： checks if the preparation of the stream object was successful （公共成员函数） | |
[编辑] 示例
#include <iostream> #include <sstream> struct Foo { char n[5]; }; std::istream& operator>>(std::istream& is, Foo& f) { std::istream::sentry s(is); if(s) is.read(f.n, 5); return is; } int main() { std::string input = " abcde"; std::istringstream stream(input); Foo f; stream >> f; std::cout.write(f.n, 5); std::cout << '\n'; }
输出：
abcde
[编辑] 另请参阅
| 提取物格式的数据 （公共成员函数） | |
| 提取字符和字符数组 原文： extracts characters and character arrays （函数模板） | |
