将float向量转换为字节向量并返回 [英] Convert float vector to byte vector and back

问题描述

我试图在float和unsigned char数组之间做一些转换（在这种情况下是std :: vector），并且遇到了一些麻烦。我已经将浮点数向量转换为无符号字符，如下所示...

  vector< float> myFloats; 
 myFloats.push_back（1.0f）; 
 myFloats.push_back（2.0f）; 
 myFloats.push_back（3.0f）; 
 $ b $ const unsigned char * bytes = reinterpret_cast< const unsigned char *>（& floats [0]）; 
 
 vector< unsigned char> byteVec; （int i = 0; i <3; i ++）
 byteVec.push_back（bytes [i]）的
 
; 
  

我希望自己做得对，如果不是这样的话部分将无法正常工作。

  //在程序后面的某个地方转换
 unsigned char * bytes =&（byteVec [0]）; //指向内存的开始
 float * floatArray = reinterpret_cast< float *>（* bytes）; （int i = 0; i <3; i ++）
 cout<< floatArray [i]<< ENDL; //错误在这里
  

我试过用（字节）代替（* bytes）部分，但打印错误的值。 （int i = 0; i <3; i ++）
cout（$ i $）
$ b

  << （float）bytes [i]<< ENDL; 
  

不知道如何从中取回原始的浮动值。

感谢您的帮助。

解决方案

解决：

我认为问题出在这里

  vector< unsigned char> byteVec; （int i = 0; i <3; i ++）
 byteVec.push_back（bytes [i]）的
 
; 
  

我将其删除并替换为

  vector< unsigned char> byteVec（bytes，bytes + sizeof（float）* myFloats.size（））; 
  

然后剩下的就可以正常工作了！

另外，请记住在这里使用（字节）而不是（*字节）

$ $ $ $ $ $ $ $ $ $ $ $ float $ floatArray = reinterpret_cast< float *>（字节）;

I'm trying to do some conversions between float and unsigned char arrays (std::vector in this case) and i've run into some troubles.

I've converted the vector of floats to unsigned char like this...

vector<float> myFloats;
myFloats.push_back(1.0f);
myFloats.push_back(2.0f);
myFloats.push_back(3.0f);

const unsigned char* bytes = reinterpret_cast<const unsigned char*>(&floats[0]);

vector<unsigned char> byteVec;

for (int i = 0; i < 3; i++)
    byteVec.push_back(bytes[i]);

I'm hoping i've done this correctly, if not that would be the reason why the next part wont work.

// converting back somewhere later in the program
unsigned char* bytes = &(byteVec[0]);    // point to beginning of memory
float* floatArray = reinterpret_cast<float*>(*bytes);

for (int i = 0; i < 3; i++)
    cout << floatArray[i] << endl;  // error here

I've tried using (bytes) instead of (*bytes) in that last part but that prints the wrong values. Doing this also printed the wrong values

for (int i = 0; i < 3; i++)
    cout << (float)bytes[i] << endl;

Not sure how to get my original float values back from this.

Thanks for any help.

解决方案

Solved:

I think the problem was here

vector<unsigned char> byteVec;

for (int i = 0; i < 3; i++)
    byteVec.push_back(bytes[i]);

I removed that and replaced it with

vector<unsigned char> byteVec(bytes, bytes + sizeof(float) * myFloats.size());

then the rest works fine!

Also, remember to use (bytes) instead of (*bytes) here

float* floatArray = reinterpret_cast<float*>(bytes);

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