std::operator<<,>>
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< cpp | string | basic string
 |
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| 在头文件 <string> 中定义
|
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| template <class CharT, class Traits, class Allocator> std::basic_ostream<CharT, Traits>& |
(1) | |
| template <class CharT, class Traits, class Allocator> std::basic_istream<CharT, Traits>& |
(2) | |
首先，构建一个std::basic_ostream::sentry对象，它刷新了tie（）“D流，如果必要的，检查错误。如果哨兵对象返回false，立即退出.
原文：
First, constructs a std::basic_ostream::sentry object, which flushes the tie()'d stream if necessary and checks for errors. If the sentry object returns false, exits immediately.
此后，如果哨兵对象返回true，确定的输出格式中相同的方式作为第3阶段的num_put::put()填充.
原文：
Afterwards, if the sentry object returns true, determines the output format padding in the same manner as stage 3 of num_put::put().
然后将每个字符序列（
str加填充的内容）到输出流os，仿佛调用os.rdbuf()->sputn(seq, n)，n=std::max(os.width(), str.size())原文：
Then stores each character from the resulting sequence (the contents of
str plus padding) to the output stream os as if by calling os.rdbuf()->sputn(seq, n), where n=std::max(os.width(), str.size())最后，调用os.width(0).
2) 首先，构建std::basic_istream::sentry对象，刷新了tie（）'D如果有必要，提取物和丢弃所有前导空格字符流，除非ios_base::skipws标志被清除，并检查错误。如果哨兵对象返回false，立即退出.
原文：
First, constructs a std::basic_istream::sentry object, which flushes the tie()'d stream if necessary, extracts and discards all leading whitespace characters unless the ios_base::skipws flag was cleared, and checks for errors. If the sentry object returns false, exits immediately.
此后，如果哨兵对象返回true，清除
strstr.erase()原文：
Afterwards, if the sentry object returns true, clears
str with str.erase()然后读取字符
is并把它们添加str如果由str.append(1, c)下列条件之一的，直到成为真正的：原文：
Then reads characters from
is and appends them to str as if by str.append(1, c), until one of the following conditions becomes true:-
N个字符，其中Nis.width()如果is.width() > 0，否则N是str.max_size()原文：Ncharacters are read, whereNisis.width()ifis.width() > 0, otherwiseNisstr.max_size() - 文件结束的条件发生在流
is原文：the end-of-file condition occurs in the streamis - std::isspace(c,is.getloc())是真正的下一个字符
cis（这个空白字符留在输入流中）.原文：std::isspace(c,is.getloc()) is true for the next charactercinis(this whitespace character remains in the input stream).
如果没有字符被提取，然后std::ios::failbit上设置
is，这可能会引发std::ios_base::failure.原文：
If no characters are extracted then std::ios::failbit is set on
is, which may throw std::ios_base::failure.最后，调用os.width(0)和破坏std::basic_istream::sentry对象.
原文：
Finally, calls os.width(0) and destroys the std::basic_istream::sentry object.
目录 |
[编辑] 例外
1)如果抛出一个异常输出过程中，可能会引发std::ios_base::failure.
2) 原文：
may throw std::ios_base::failure if an exception is thrown during output.
可能会引发std::ios_base::failure乃摘录自
is如果没有字符（如流位于文件末尾的空白，或由只），或在输入过程中，如果抛出一个异常.原文：
may throw std::ios_base::failure if no characters are extracted from
is (e.g the stream is at end of file, or consists of whitespace only), or if an exception is thrown during input.[编辑] 参数
| os | - | 字符输出流
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| is | - | 字符输入流
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| str | - | 字符串被插入或提取
原文： the string to be inserted or extracted |
[编辑] 返回值
1) os
2) is
[编辑] 示例
#include <iostream> #include <string> int main() { std::string greeting = "Hello, whirled!" std::cout << greeting << '\n'; }
输出：
Hello, whirled!
