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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