Question

So I know I have asked this question before, however, I am still stuck and before I can move on with my project. Basically, I’m trying to read in a .wav file, I have read in all of the required header information and then stored all the data inside a char array. This is all good, however, I then recast the data as an integer and try and output the data.

I have tested the data in MatLab, however, I get very different results:

Matlab -0.0078

C++: 1031127695

Now these are very wrong results, and someone kindly from here said it’s because I’m outputting it as an integer, however, I have tried pretty much every single data type and still get the wrong results. Someone has suggestion that it could be something to do with Endianness (http://en.wikipedia.org/wiki/Endianness) .. Does this seem logical?

Here is the code:

bool Wav::readHeader(ifstream &file)
{

file.read(this->chunkId,                                 4);
file.read(reinterpret_cast<char*>(&this->chunkSize),     4);
file.read(this->format,                                  4);

file.read(this->formatId,                                4);
file.read(reinterpret_cast<char*>(&this->formatSize),    4);
file.read(reinterpret_cast<char*>(&this->format2),       2);
file.read(reinterpret_cast<char*>(&this->numChannels),   2);
file.read(reinterpret_cast<char*>(&this->sampleRate),    4);
file.read(reinterpret_cast<char*>(&this->byteRate),      4);
file.read(reinterpret_cast<char*>(&this->align),         2);
file.read(reinterpret_cast<char*>(&this->bitsPerSample), 4);

char testing[4] = {0};
int testingSize = 0;

while(file.read(testing, 4) && (testing[0] != 'd' ||
                                testing[1] != 'a' ||
                                testing[2] != 't' ||
                                testing[3] != 'a'))
{

file.read(reinterpret_cast<char*>(&testingSize), 4);
file.seekg(testingSize, std::ios_base::cur);

  }

      this->dataId[0] = testing[0];
      this->dataId[1] = testing[1];
      this->dataId[2] = testing[2];
      this->dataId[3] = testing[3];
     file.read(reinterpret_cast<char*>(&this->dataSize),     4);

     this->data = new char[this->dataSize];

     file.read(data,                     this->dataSize);

     unsigned int *te;

     te = reinterpret_cast<int*>(&this->data);

     cout << te[3];

     return true;
     }

Any help would be really appreciated. I hope I’ve given enough details.

Thank you.

Answer 1

I think there’re several issues with your code. One of them are the casts, for instance this one:

 unsigned int *te;                           
 te = reinterpret_cast<int*>(&this->data);     // (2)
 cout << te[3];                                

te is a pointer to unsigned int, while you try to cast to a pointer to int. I would expect compilation error at line (2)…

And what do you mean by te[3]? I expect some garbage from *(te + 3) memory location to be outputed here.