串联不同长度的二进制数 [英] Concatenate binary numbers of different lengths

问题描述

因此​​，我有3个数字。一个是字符，另外两个是 int16_t （又名短 S，但根据表，我发现短裤就不能可靠地为16位）。

我想将它们串联在一起。所以说，他们的价值观是：

10010001

1111111111111101

1001011010110101

我想和落得一个长长包含：

1001000111111111111111011001011010110101000000000000000000000000

使用一些解决方案，我在网上找到的，我想出了这一点：

  long long结果;
结果= NUM​​1;
结果=（结果＆LT;＆LT; 8）| NUM2;
结果=（结果＆LT;＆LT; 24）| NUM3;
 

但它不工作;这让我很奇怪的数字时，它的德codeD。

在情况下，有一个与我的解码code的一个问题，那就是：

 字符NUM1 = NUM​​＆安培; 0xFF的;
int16_t NUM2 = NUM​​＆LT;＆LT; 8和; 0xFFFF的;
int16_t NUM3 = NUM​​＆LT;＆LT; 24安培; 0xFFFF的;
 

这是怎么回事？我怀疑它有一个长长，但我不能完全换我的头周围，我要容纳更多的号码后来<大小做/ p>

解决方案

要得到正确的位模式为你的要求，你使用768,16：

 结果= NUM​​1;
结果=（结果＆LT;＆LT; 16）| NUM2;
结果=（结果＆LT;＆LT; 16）| NUM3;
结果＆LT;＆LT = 24;
 

这将产生你所要求的精确位模式，24位在LSB-留底0：

  1001000111111111111111011001011010110101000000000000000000000000
 

So I have 3 numbers. One is a char, and the other two are int16_t (also known as shorts, but according to a table I found shorts won't reliably be 16 bits).

I'd like to concatenate them together. So say that the values of them were:

10010001

1111111111111101

1001011010110101

I'd like to end up with a long long containing:

1001000111111111111111011001011010110101000000000000000000000000

Using some solutions I've found online, I came up with this:

long long result;
result = num1;
result = (result << 8) | num2;
result = (result << 24) | num3;

But it doesn't work; it gives me very odd numbers when it's decoded.

In case there's a problem with my decoding code, here it is:

char num1 = num & 0xff;
int16_t num2 = num << 8 & 0xffff;
int16_t num3 = num << 24 & 0xffff;

What's going on here? I suspect it has to do with the size of a long long, but I can't quite wrap my head around it and I want room for more numbers in it later.

解决方案

To get the correct bit-pattern as you requested, you shoud use:

result = num1;
result = (result << 16) | num2;
result = (result << 16) | num3; 
result<<=24;

This will yield the exact bit pattern that you requested, 24 bits at the lsb-end left 0:

1001000111111111111111011001011010110101000000000000000000000000

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