Is `std::endl` in C a Performance Bottleneck?

The C iostream endl Fiasco: Unwarranted Flushes and Performance Issues

The infamous "endl" fiasco in C stems from the excessive use of std::endl in place of the simpler 'n' newline character. While std::endl has its legitimate applications, its frequent misuse has created a performance challenge within the C community.

std::endl not only inserts a newline into a stream but also calls the std::flush function, which forces the buffer to be flushed. However, in most cases, such frequent flushing is unnecessary and can negatively impact performance.

Many programmers have a habit of mindlessly using std::endl throughout their code, assuming it to be the default and preferred method for a newline. This practice has become so widespread that even experienced programmers sometimes forget about the overhead of std::flush.

The performance issue arises because when using std::endl, the buffer is flushed even when it is not necessary, such as after a simple std::cout statement. This frequent flushing can lead to latency and performance degradation, especially in I/O-intensive scenarios.

While std::endl can be useful for explicitly flushing the buffer when necessary (e.g., after important outputs), its overuse often outweighs any potential benefit. However, for most newline scenarios, 'n' is a more efficient choice.

In summary, the "endl fiasco" refers to the unwarranted and excessive use of std::endl in C code, which can lead to slower performance and unnecessarily long output streams. Therefore, programmers should be mindful of their newline usage and consider using 'n' whenever possible to avoid the drawbacks associated with std::endl.

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