在C ++中初始化数组 [英] Initialising arrays in C++

问题描述

无处不在，我看到有人争辩说，未初始化的变量是坏的，我当然同意和理解为什么 - 然而;我的问题是，有时候你不想这样做吗？

Everywhere I look there are people who argue vociferously that uninitialised variables are bad and I certainly agree and understand why - however; my question is, are there occasions when you would not want to do this?

例如，取代码：

char arrBuffer[1024] = { '\0' };

在不初始化数组的情况下，

Does NULLing the entire array create a performance impact over using the array without initialising it?

推荐答案

我假设一个堆栈初始化，因为静态数组是自动初始化的。

G ++ output

I assume a stack initialization because static arrays are auto-initialized.
G++ output

   char whatever[2567] = {'\0'};
   8048530:       8d 95 f5 f5 ff ff       lea    -0xa0b(%ebp),%edx
   8048536:       b8 07 0a 00 00          mov    $0xa07,%eax
   804853b:       89 44 24 08             mov    %eax,0x8(%esp)
   804853f:       c7 44 24 04 00 00 00    movl   $0x0,0x4(%esp)
   8048546:       00 
   8048547:       89 14 24                mov    %edx,(%esp)
   804854a:       e8 b9 fe ff ff          call   8048408 <memset@plt>

所以，你用{'\0'}初始化并调用memset是的，你有一个性能打击。

So, you initialize with {'\0'} and a call to memset is done, so yes, you have a performance hit.

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