Scalar Value Types

How each protobuf scalar type maps onto common language types.

Proto Type	Notes	C++	C#	Go	Java	PHP	Python	Ruby
double	—	double	double	float64	double	float	float	Float
float	—	float	float	float32	float	float	float	Float
int32	Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint32 instead.	int32	int	int32	int	integer	int	Bignum or Fixnum (as required)
int64	Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint64 instead.	int64	long	int64	long	integer/string	int/long	Bignum
uint32	Uses variable-length encoding.	uint32	uint	uint32	int	integer	int/long	Bignum or Fixnum (as required)
uint64	Uses variable-length encoding.	uint64	ulong	uint64	long	integer/string	int/long	Bignum or Fixnum (as required)
sint32	Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int32s.	int32	int	int32	int	integer	int	Bignum or Fixnum (as required)
sint64	Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int64s.	int64	long	int64	long	integer/string	int/long	Bignum
fixed32	Always four bytes. More efficient than uint32 if values are often greater than 2^28.	uint32	uint	uint32	int	integer	int	Bignum or Fixnum (as required)
fixed64	Always eight bytes. More efficient than uint64 if values are often greater than 2^56.	uint64	ulong	uint64	long	integer/string	int/long	Bignum
sfixed32	Always four bytes.	int32	int	int32	int	integer	int	Bignum or Fixnum (as required)
sfixed64	Always eight bytes.	int64	long	int64	long	integer/string	int/long	Bignum
bool	—	bool	bool	bool	boolean	boolean	boolean	TrueClass/FalseClass
string	A string must always contain UTF-8 encoded or 7-bit ASCII text.	string	string	string	String	string	str/unicode	String (UTF-8)
bytes	May contain any arbitrary sequence of bytes.	string	ByteString	[]byte	ByteString	string	str	String (ASCII-8BIT)