byte + byte = int ... 为什么?

问题描述

看看这段 C# 代码:

Looking at this C# code:

byte x = 1;
byte y = 2;
byte z = x + y; // ERROR: Cannot implicitly convert type 'int' to 'byte'

对 byte(或 short)类型执行的任何数学运算的结果都会隐式转换回整数.解决方案是将结果显式转换回一个字节:

The result of any math performed on byte (or short) types is implicitly cast back to an integer. The solution is to explicitly cast the result back to a byte:

byte z = (byte)(x + y); // this works

我想知道为什么?它是建筑的吗?哲学?

What I am wondering is why? Is it architectural? Philosophical?

我们有:

• int + int = int
• long + long = long
• float + float = float
• double + double = double

• int + int = int
• long + long = long
• float + float = float
• double + double = double

为什么不呢:

• 字节 + 字节 = 字节
• short + short = short?

• byte + byte = byte
• short + short = short?

一点背景知识:我正在对小数"(即 < 8)执行一长串计算，并将中间结果存储在一个大数组中.使用 byte 数组(而不是 int 数组)更快(因为缓存命中).但是通过代码传播的大量字节转换使其更加难以阅读.

A bit of background: I am performing a long list of calculations on "small numbers" (i.e. < 8) and storing the intermediate results in a large array. Using a byte array (instead of an int array) is faster (because of cache hits). But the extensive byte-casts spread through the code make it that much more unreadable.

推荐答案

你的代码片段的第三行:

The third line of your code snippet:

byte z = x + y;

其实就是

byte z = (int) x + (int) y;

因此，对字节没有 + 操作，字节首先转换为整数，两个整数相加的结果是一个(32 位)整数.

So, there is no + operation on bytes, bytes are first cast to integers and the result of addition of two integers is a (32-bit) integer.

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