C++核心准则​SL.io.50：避免使用endl

SL.io.50: Avoid endl

SL.io.50：避免使用endl

Reason（原因）

The endl manipulator is mostly equivalent to '\n' and "\n"; as most commonly used it simply slows down output by doing redundant flush()s. This slowdown can be significant compared to printf-style output.

endl操纵符差不多等于是'\ n'和“ \ n”；使用它最常见的结果是通过执行多余的flush（）来减慢输出速度。与printf样式的输出相比，这种速度下降可能会显著。

Example（示例）

cout << "Hello, World!" << endl;    // two output operations and a flush
cout << "Hello, World!\n";          // one output operation and no flush

Note（注意）

For cin/cout (and equivalent) interaction, there is no reason to flush; that's done automatically. For writing to a file, there is rarely a need to flush.

对于cin / cout（和等效的）交互，没有理由刷新；那是自动完成的。对于文件写入，几乎不需要刷新。

Note（注意）

Apart from the (occasionally important) issue of performance, the choice between '\n' and endl is almost completely aesthetic.

除了（有时很重要的）性能问题之外，在'\ n'和endl之间进行选择几乎是完全取决于美感的。

原文链接

https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#slio50-avoid-endl