初始化数组在C ++中 [英] Initialising arrays in C++

问题描述

我到处看看还有谁认为这叫喊变量未初始化是坏，我当然同意并理解为什么人们 - 但是，我的问题是，是否有场合，你不会想这样做？

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，以code：

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

是否归零整个阵列创造超过使用数组初始化没有它的性能影响？

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。结果
G ++输出

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，你初始化{'\\ 0'}和memset的呼叫完成的，所以是的，你有性能损失。

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

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