Read UInt types in binary - c++

Question

I am implementing a MidiReader
And it need me to read weather MSB First or LSB First UInts(8, 16, 32 or 64).
I know little about binary and types so I'm currently copying other's code from C#.
class ByteArrayReader
{
public:
unsigned char* ByteArray;
unsigned int Size;
unsigned int Index = 0;
ByteArrayReader(unsigned char* byteArray)
{
if (byteArray == NULL)
{
throw byteArray;
}
ByteArray = byteArray;
Size = (unsigned int)sizeof(byteArray);
Index = 0;
}
char inline Read()
{
return ByteArray[Index++];
}
void inline Forward(unsigned int length = 1)
{
Index += length;
}
void inline Backward(unsigned int length = 1)
{
if (length > Index)
{
throw length;
}
Index -= length;
}
bool operator==(ByteArrayReader) = delete;
};
These are what I copied:
uint16_t inline ReadUInt16()
{
return (uint16_t)((Read() << 8) | Read());
}
uint32_t inline ReadUInt32()
{
return (uint32_t)((((((Read() << 8) | Read()) << 8) | Read()) << 8) | Read());
}
But it's said that one of it reads MSB First UInt. So I want to ask how to read UInt types from binaries elegantly, also learning how uint is represented in bytes.

Answer 1

The part
(uint32_t)((((((Read() << 8) | Read()) << 8) | Read()) << 8) | Read());
is undefined behavior because each call to Read method increments a counter called Index and there is no strict order of computation of them by compiler.
It would be better if they were computed in order like this:
auto chunk1 = Read(); // Index=x
auto chunk2 = Read(); // Index=x+1
auto chunk3 = Read(); // Index=x+2
...
auto result = chunk1 << 8 | chunk2<<8 ...
to be sure incrementations are happening in order.
Order of bytes is different between little-endian and big-endian systems. Here it is asked: Detecting endianness programmatically in a C++ program

Answer 2

Try this:
uint32_t inline ReadUInt32MSBfirst()
{
auto b1 = Read();
auto b2 = Read();
auto b3 = Read();
auto b4 = Read();
return (uint32_t)((b1 << 24) | (b2 << 16) | (b3 << 8) | b4);
}
uint32_t inline ReadUInt32LSBfirst()
{
auto b1 = Read();
auto b2 = Read();
auto b3 = Read();
auto b4 = Read();
return (uint32_t)(b1 | (b2 << 8) | (b3 << 16) | (b4 << 24));
}