Microsoft Visual Studio，在调试中不显示unsigned char，截断int t [英] Microsoft Visual Studio, does not display unsigned char in debug, truncation of int t
问题描述
我最近开始学习C ++，为了练习练习，我使用的是Microsoft Visual Studio。
我试图重新创建初始化-1的效果一个unsigned char（因此返回255）。然而，当编译代码时，它显示为未定义，警告我将int截断为unsigned char，并警告我正在截断常量值。
我得到了一个int不会提升到一个unsigned char，但是不应该认识到-1转换为255作为unsigned char吗？或者我错过了使用Visual Studio特有的东西？
调试时，我尝试为unsigned char做一个cout，但只显示一个空格。以下是cc
澄清的代码：
#include" stdafx.h"
#include< iostream>
使用命名空间std;
int main（）
{
unsigned char c =' '-1'';
cout<< c<< endl;
返回0;
}
Hi, I''ve recently started studying C++ and in order to practice exercises I am using Microsoft Visual Studio.
I am attempting to recreate the effect of initializing -1 to an unsigned char (thus returning 255). When compiling the code however, it shows as undefined, warning that I am truncating an int into an unsigned char, as well as warning that I am truncating a constant value.
I get that an int does not promote up to an unsigned char, but shouldn''t the ide recognize that -1 converts to 255 as an unsigned char? Or am I missing something that is particular to using Visual studio?
When debugging, I try to do a cout for the unsigned char, but only a blank space shows. Here is the code for cc
clarification:
#include "stdafx.h"
#include <iostream>
using namespace std;
int main()
{
unsigned char c = ''-1'';
cout << c << endl;
return 0;
}
推荐答案
编辑：最初我试图只指定-1到unsigned char，在没有运气之后，我尝试将-1放在单引号中。这是带单引号的代码，但即使没有引号我也有同样的问题。抱歉这个混乱
edit: originally I tried to assign just -1 to the unsigned char, and after not having luck with that I tried putting the -1 in single quotes '' . This is the code with the single quotes, but I have the same issue even without quotes. Sorry for that confusion
这段代码：
This code:
- 如果编译器使用两个'的补码格式，则将1存储为255。我不相信C标准要求使用两个补码。你必须非常努力地找到一个不使用两个补码表示法的编译器，但这不是重点。您依赖于实现定义的行为。
-1 is stored as 255 if the compiler uses two''s complement format. I don''t believe the C Standard mandates the use of two''s complement. You would have to look very hard to find a compiler that doesn''t use two''s complement notation, but that''s not the point. You are relying on implementation-defined behavior.
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