在C ++中使用size_t是个好习惯吗？

问题描述

我已经看到人们使用 size_t ，当它们意味着一个无符号整数。例如：

  class Company {
 size_t num_employees_; 
 // ... 
}; 
  

这是好的做法吗？一件事是你必须包括< cstddef> 。应该是 unsigned int 吗？或者甚至只是 int ？

使用 int 听起来很吸引我，因为它避免了像这样的愚蠢的错误（因为人们经常使用 int ）：

  for（int i = num_employees_  -  1; i& = 0; --i）{
 //使用employee_ [i] 
执行某项操作
  

可能与 int 的大小不同。 / p>

对于像员工人数等等，这种差异通常是无关紧要的;一个人有多于2 ^ 32名员工？但是，如果您使用 size_t 代替 int 文件系统支持64位文件。

请注意，对象大小（由 sizeof 获得） code> size_t ，而不是 int 或 unsigned int ;相应地，对于两个指针之间的差异（例如，& a [5] - & a [0] =< = ptrdiff_t（5））。

I've seen people use size_t whenever they mean an unsigned integer. For example:

class Company {
  size_t num_employees_;
  // ...
};

Is that good practice? One thing is you have to include <cstddef>. Should it be unsigned int instead? Or even just int?

Just using int sounds attractive to me since it avoids stupid bugs like these (because people do often use int):

for(int i = num_employees_ - 1; i >= 0; --i) {
   // do something with employee_[i]
}

解决方案

size_t may have different size to int.

For things like number of employees, etc., this difference usually is inconsequential; how often does one have more than 2^32 employees? However, if you a field to represent a file size, you will want to use size_t instead of int, if your filesystem supports 64-bit files.

Do realise that object sizes (as obtained by sizeof) are of type size_t, not int or unsigned int; also, correspondingly, there is a ptrdiff_t for the difference between two pointers (e.g., &a[5] - &a[0] == ptrdiff_t(5)).

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