Question

I want to extract some integers from a file using C++, but I am not sure if I am doing it correctly.

My code in VB6 is the following:

Redim iInts(240) As Integer
Open "m:\dev\voice.raw" For Binary As #iFileNr
Get #iReadFile, 600, iInts() 'Read from position 600 and read 240 bytes

My conversion to C++ is the following:

vector<int>iInts
iInts.resize(240)

FILE* m_infile;
string filename="m://dev//voice.raw";

if (GetFileAttributes(filename.c_str())==INVALID_FILE_ATTRIBUTES)
{
  printf("wav file not found");
  DebugBreak();
} 
else 
{
  m_infile = fopen(filename.c_str(),"rb");
}

But now I don’t know how to continue from there, and I also don’t know if “rb” is correct.

Answer 1

I don’t know how VB reads a file but if you need to read integers from a file try:

m_infile = fopen(myFile, "rb")
fseek(m_infile, 600 * sizeof(int), SEEK_SET);
// Read the ints, perhaps using fread(...)
fclose(myFile);

Or you can use the C++ way using ifstream.

Full example with streams (note, you should add error checking):

#include <ifstream>

void appendInts(const std::string& filename, 
                unsigned int byteOffset, 
                unsigned int intCount,
                const vector<int>& output)
{
    std::ifstream ifs(filename, std::ios::base::in | std::ios::base::binary);
    ifs.seekg(byteOffset);
    for (unsigned int i = 0; i < intCount; ++i)
    {
        int i;
        ifs >> i;
        output.push_back(i);
    }
}

...

std::vector<int> loadedInts;
appendInts("myfile", 600, 60, loadedInts);