转移字节，其余铸造到int类型（有兴趣补） [英] Shifting bytes and remaining values casted to int (interested in two's complement)

问题描述

为什么code，你见下文给出这些结果？

Why does the code that you see below give these results?

void loop() {
    byte test = 00000101;
    Serial.print("The byte test is: ");
    Serial.println(test);
    int x = (int)test;
    int y = (int)test<<8;
    Serial.print("The int x is: ");
    Serial.println(x);
    Serial.print("The int shifted y is: ");
    Serial.println(y);

    byte tost = 10000001;
    int z = test + tost;
    Serial.print("The int z is: ");
    Serial.println(z);

    delay(1000);
}

结果

字节测试：65

的int x为：65

The int x is: 65

的int转移y为：16640

The int shifted y is: 16640

的int z是：194

The int z is: 194

虽然如果我改变了测试，以00000001它执行很大的：

While if I change the test to 00000001 it performs great:

改code：

void loop() {
    byte test = 00000001;
    Serial.print("The byte test is: ");
    Serial.println(test);
    int x = (int)test;
    int y = (int)test<<8;
    Serial.print("The int x is: ");
    Serial.println(x);
    Serial.print("The int shifted y is: ");
    Serial.println(y);

    byte tost = 10000001;
    int z = test + tost;
    Serial.print("The int z is: ");
    Serial.println(z);

    delay(1000);
}

结果：

The byte test is: 1

The int x is: 1

The int shifted y is: 256

The int z is: 130

我的问题是，我有我想从数据寄存器从读取加速度计两个字节。该值存储在补所以我想既然检查如果我破坏值，因为我必须做一些移动wire.read 返回一个字节，有些人说是有符号和一些未签名。

My problem is that I have two bytes that I want to read from data registers from an accelerometer. The value is stored in two's complement so I wanted to check since wire.read returns a byte that some people say that is signed and some unsigned if I destroy the values, because I have to do some shifting.

所以，我想检查，如果我有一个字节并且我推诿，并将其存放到一个int，我得到什么样的价值观做的，我想测试，如果不知何故，我可以存储一个字节数组内签署字节值。

So I wanted to check if I have a byte and I try to shift it and store it to an int, what values do I get, and I want to test if somehow I can store signed byte values inside a byte array.

推荐答案

上面显示的答案是正确的，因为阿列克西伏龙芝说从0开始编号为八进制。

The answer shown above is correct as Alexy Frunze said number starting with 0 is octal .

000000101 is 65 not 5
65 << 8 =16640
10000001 in decimal is 129
129+65 = 194

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