Conversions from signed integral types

When a signed integer is converted to an integer or a floating-point type, the value is unchanged if it's representable in the result type.

When a signed integer is converted to an integer of greater size, the value is sign-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:

int i = -3;
unsigned short u;

u = i;
printf_s( "%hu\n", u );  // Prints 65533

When the compiler converts a signed 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.

For information about the sizes of integral and floating-point types, see Storage of basic types.

The following table summarizes conversions from signed integral types. It assumes the char type is signed by default. If you use a compile-time option to change the default for the char type to unsigned, the conversions given in the Conversions from unsigned integral types table for the unsigned char type apply, instead of the conversions in this table.

Microsoft Specific

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

END Microsoft Specific

Table of conversions from signed integral types

From	To	Method
char1	short	Sign-extend
char	long	Sign-extend
char	long long	Sign-extend
char	unsigned char	Preserve pattern; high-order bit loses function as sign bit
char	unsigned short	Sign-extend to short; convert short to unsigned short
char	unsigned long	Sign-extend to long; convert long to unsigned long
char	unsigned long long	Sign-extend to long long; convert long long to unsigned long long
char	float	Represent exactly as float
char	double	Represent exactly as double
char	long double	Represent exactly as long double
short	char	Preserve low-order byte
short	long	Sign-extend
short	long long	Sign-extend
short	unsigned char	Preserve low-order byte
short	unsigned short	Preserve bit pattern; high-order bit loses function as sign bit
short	unsigned long	Sign-extend to long; convert long to unsigned long
short	unsigned long long	Sign-extend to long long; convert long long to unsigned long long
short	float	Represent exactly as float
short	double	Represent exactly as double
short	long double	Represent exactly as long double
long	char	Preserve low-order byte
long	short	Preserve low-order word
long	long long	Sign-extend
long	unsigned char	Preserve low-order byte
long	unsigned short	Preserve low-order word
long	unsigned long	Preserve bit pattern; high-order bit loses function as sign bit
long	unsigned long long	Sign-extend to long long; convert long long to unsigned long long
long	float	Represent as float. If long can't be represented exactly, some precision is lost.
long	double	Represent exactly as double
long	long double	Represent exactly as long double
long long	char	Preserve low-order byte
long long	short	Preserve low-order word
long long	long	Preserve low-order dword
long long	unsigned char	Preserve low-order byte
long long	unsigned short	Preserve low-order word
long long	unsigned long	Preserve low-order dword
long long	unsigned long long	Preserve bit pattern; high-order bit loses function as sign bit
long long	float	Represent as float. If long long can't be represented exactly, some precision is lost.
long long	double	Represent as double. If long long can't be represented exactly as a double, some precision is lost.
long long	long double	Represent as double. If long long can't be represented exactly as a double, some precision is lost.

¹ All char entries assume that the char type is signed by default.

See also

Assignment conversions