A easiest way to read larger than 2GB file size using C/C++

I have tested it for 10GB file reading, You could use it
#define INT __int64

void read(INT startByte, INT endByte) {
	FILE *bFile;

	bFile = fopen((mainPath).c_str(), "rb");

	if (bFile == NULL)
	{
		fprintf(stderr, "File error in ", startByte, endByte);
		exit(1);
	}

	size_t result;
	double s = clock();

	long     readLength;
	__int64  fileSize = 0;
	__int64  i = 0;
	__int64  sum = 0;
	__int64  value = 200;
	__int64  intFileEndByte;

	this - > startByte = startByte;
	this - > endByte = (INT)(this - > startByte + INT(this - > getRamSize()));        // upper limit may be -)1

	_fseeki64(bFile, 0, SEEK_END);

	intFileEndByte = _ftelli64(bFile);

	if (intFileEndByte < this - > endByte)
		this - > endByte = intFileEndByte - 1;

	_fseeki64(bFile, startByte, SEEK_SET);
	readLength = (long)(this - > endByte - this - > startByte + 1);
	if (bFile != NULL)
		result = fread(this - > data, 1, readLength, bFile);
	else
		printf("File reading error\n");

	INT size = (INT)result;
	if (result != readLength) {
		fputs("\nReading error\n", stderr);
	}

	fclose(bFile);
}