这是不可避免的有符号和无符号整数比较吗？ [英] Is this an unavoidable signed and unsigned integer comparison?

问题描述

可能不是，但我不能想到一个很好的解决方案。我不是C ++的专家。

Probably not, but I can't think of a good solution. I'm no expert in C++ yet.

最近我把很多 int 转换为 unsigned int 。基本上不应该为负的一切都是无符号的。这移除了MinGW的许多警告：

Recently I've converted a lot of ints to unsigned ints in a project. Basically everything that should never be negative is made unsigned. This removed a lot of these warnings by MinGW:

警告：有符号和无符号整数表达式之间的比较[-Wsign-compare] >

warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

我喜欢它。它使程序更健壮，代码更具描述性。然而，有一个地方，他们仍然发生。它看起来像这样：

I love it. It makes the program more robust and the code more descriptive. However, there is one place where they still occur. It looks like this:

unsigned int subroutine_point_size = settings->get<unsigned int>("subroutine_point_size");
...
for(int dx = -subroutine_point_size;dx <= subroutine_point_size;dx++) //Fill pixels in the point's radius.
{
    for(int dy = -subroutine_point_size;dy <= subroutine_point_size;dy++)
    {
        //Do something with dx and dy here.
    }
}

在这种情况下，我不能使 dx 和 dy 无符号。

In this case I can't make dx and dy unsigned. They start out negative and depend on comparing which is lesser or greater.

我不喜欢使用 subroutine_point_size 签署，虽然这是较小的邪恶。它指示在传递图像时内核的大小，并且内核大小不能为负（对于用户来说，将内核大小设置为大于100的内容大小可能是不明智的，但是设置文件允许数字达到2 ^ 32 - 1）。

I don't like to make subroutine_point_size signed either, though this is the lesser evil. It indicates a size of a kernel in a pass over an image, and the kernel size can't be negative (it's probably unwise for a user ever to set this kernel size to anything more than 100 but the settings file allows for numbers up to 2^32 - 1).

所以似乎没有办法转换任何变量来解决这个问题。有没有办法摆脱这个警告，并解决这个整洁？

So it seems there is no way to cast any of the variables to fix this. Is there a way to get rid of this warning and solve this neatly?

我们使用C ++ 11，使用GCC编译Windows，Mac和各种Unix发行版。

We're using C++11, compiling with GCC for Windows, Mac and various Unix distributions.

推荐答案

将变量投射到 long int 或 long long int 类型同时给出unsigned int（0..2 ^ 32-1）的范围和符号。

Cast the variables to a long int or long long int type giving at the same time the range of unsigned int (0..2^32-1) and sign.

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