Conversions from unsigned integral types

When an unsigned integer is converted to an integer or floating-point type, if the original value is representable in the result type the value is unchanged.

When the compiler converts an unsigned integer to an integer of greater size, the value is zero-extended. When converted to an integer of smaller size, the high-order bits are truncated. The result is interpreted using the result type, as shown in this example:

unsigned k = 65533;
short j;

j = k;
printf_s( "%hd\n", j );   // Prints -3

When the compiler converts an unsigned integer to a floating-point type, if the original value isn't representable exactly in the result type, the result is the next higher or lower representable value.

See Storage of basic types for information about the sizes of integral and floating-point types.

Microsoft Specific

In the Microsoft compiler, unsigned (or unsigned int) and unsigned long are distinct but equivalent types. Conversion of an unsigned int value proceeds in the same way as conversion of an unsigned long.

END Microsoft Specific

The following table summarizes conversions from unsigned integral types.

Table of conversions from unsigned integral types

From	To	Method
unsigned char	char	Preserve bit pattern; high-order bit becomes sign bit
unsigned char	short	Zero-extend
unsigned char	long	Zero-extend
unsigned char	long long	Zero-extend
unsigned char	unsigned short	Zero-extend
unsigned char	unsigned long	Zero-extend
unsigned char	unsigned long long	Zero-extend
unsigned char	float	Convert exactly to float
unsigned char	double	Convert exactly to double
unsigned char	long double	Convert exactly to long double
unsigned short	char	Preserve low-order byte
unsigned short	short	Preserve bit pattern; high-order bit becomes sign bit
unsigned short	long	Zero-extend
unsigned short	long long	Zero-extend
unsigned short	unsigned char	Preserve low-order byte
unsigned short	unsigned long	Zero-extend
unsigned short	unsigned long long	Zero-extend
unsigned short	float	Convert exactly to float
unsigned short	double	Convert exactly to double
unsigned short	long double	Convert exactly to long double
unsigned long	char	Preserve low-order byte
unsigned long	short	Preserve low-order word
unsigned long	long	Preserve bit pattern; high-order bit becomes sign bit
unsigned long	long long	Zero-extend
unsigned long	unsigned char	Preserve low-order byte
unsigned long	unsigned short	Preserve low-order word
unsigned long	unsigned long long	Zero-extend
unsigned long	float	Convert to nearest representable float
unsigned long	double	Convert exactly to double
unsigned long	long double	Convert exactly to long double
unsigned long long	char	Preserve low-order byte
unsigned long long	short	Preserve low-order word
unsigned long long	long	Preserve low-order dword
unsigned long long	long long	Preserve bit pattern; high-order bit becomes sign bit
unsigned long long	unsigned char	Preserve low-order byte
unsigned long long	unsigned short	Preserve low-order word
unsigned long long	unsigned long	Preserve low-order dword
unsigned long long	float	Convert to nearest representable float
unsigned long long	double	Convert to nearest representable double
unsigned long long	long double	Convert to nearest representable long double

See also

Assignment conversions