C代码运行得更快吗？ [英] Does C code run faster?

问题描述

从Objective-C调用C代码是否有任何性能提升？

Is there any performance gain in calling C code from Objective-C?

我读过某些地方，与使用函数调用的其他语言相比，消息传递速度较慢。因此，如果我从Objective-C代码调用C函数，我是否避免了消息传递开销？

I've read somewhere that message passing is slower compared to other languages that use function calling. So if I call a C function from Objective-C code, am I avoiding the messaging overhead?

在优化性能时，是否建议练习编写最关键的函数和C中的程序而不是使用Objective-C对象？

When optimizing for performance, is it recommended practice to code the most critical functions and procedures in C instead of using Objective-C objects?

编辑：

鉴于有关过早优化和代码可读性的答案数量，我我想澄清我没有考虑常规应用程序，但是非常具体的应用程序，例如：

Given the amount of answers warning about premature optimization and code readability, I want to clarify that I was not thinking on regular applications, but very specific ones such as:

• 图形


• 加密或压缩算法。


• 数学

一般来说，功能或程序不需要OO设计，并且打算用参数多次调用。

And in general, functions or procedures that do not need OO design and are intended to be called many times with parameters.

推荐答案

这是基准测试，用于将消息传递与调用C函数进行比较。以下是调用斐波那契函数的不同实现大约14亿次的结果。

This is a benchmark that compares messaging to calling C functions. Here are the results of calling different implementations of the fibonacci function about 1.4 billion times.

Message Passing 23.495 seconds
IMP Calling     16.033 seconds
C Function      9.709 seconds

所以是的，调用时有一些开销Objective C方法。但是，除了在某些情况下，这不会影响您的应用程序的性能。事实上，消息传递仍然比大多数其他操作更有效例如浮点除法。

So yes, there is some overhead when calling an Objective C method. But, except in some situations, this is not what will impact the performance of your app. In fact, messaging is still more efficient than most other operations such as floating-point division.

此外，大多数应用程序花费大部分时间等待用户输入，下载数据等。

In addition, the majority apps spend most time waiting for user input, downloading data, etc.

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