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How do I use an unsigned char* string with the LoadFromString function?

The client wrapper class' LoadFromString function accepts a std::string which can contain binary data. The trick is to convert the unsigned char data that you have into a std::string. The following C++ example should do the trick. It's tested and seems to work okay.

// Open the file
FILE *fileHandle = fopen("test.pdf", "rb");

// Get the length of the file
fseek(fileHandle, 0, SEEK_END);
long fileLength = ftell(fileHandle);

// Go back to the beginning
fseek(fileHandle, 0, SEEK_SET);

// Allocate some memory using unsigned char
unsigned char *fileBytes = (unsigned char *)malloc(fileLength);

// Read the file contents
fread(fileBytes, fileLength, 1, fileHandle);
fclose(fileHandle);

// Convert the unsigned char array into a std::string
std::string fileBytesStr = std::string(
    reinterpret_cast<char*>(fileBytes), fileLength);

// Create an instance of the Quick PDF Library DLL interface class
QuickPDFDLL0716 QP("D:\\QPL\\QuickPDFDLL0716.dll");

// Unlock the library
QP.UnlockKey("jj9a947m5u14zp6cg87f9nj3y");

int loadResult = QP.LoadFromString(fileBytesStr);
if (loadResult == 1)
{
    // Success
}
else
{
    // Failure
}