Implementation Dependency - Integers (F.3.5)

The following table shows the storage occupied and the range of various integer types. (3.1.2.5)

When an integer is converted to a signed char, the lowest byte of the integer is used to represent the char. (3.2.1.2)

When an integer is converted to a shorter signed integer, the lowest 2 bytes of the integer are used to represent the short int. (3.2.1.2)

When an unsigned integer is converted to a signed integer of equal length, the bit pattern is preserved, and the high-order bit becomes the sign bit. (3.2.1.2)

Bitwise operations (Inclusive OR (|), AND (&), Exclusive OR (^)) on a signed integer use the bit pattern of the signed quantity. (3.3)

If either operand of integer division is negative, the result of the / operator is the largest integer less than or equal to the algebraic quotient. (3.3.5)

When a bitwise right shift (>>) of a negative signed integral type is used, vacated bits are filled with ones. (3.3.7) When a bitwise right shift () of a non-negative signed integral type or an unsigned integral type is used, vacated bits are filled with zeros.

When using long long in your programs, the following rules apply:

• The size of pointers remains 32-bit.
• An integer constant has type long long int only if it is suffixed by the letters ll.
• An integer constant with suffix ll has type long long int or unsigned long long int. An integer with suffix ull or llu has type unsigned long long int.
• Integral promotions are unchanged. Integral promotions are not performed on long long ints.
• Conversion of an integral type to long long int only occurs if one of the operands in the expression being evaluated has type long long int.
• When a value of float type is converted to long long type, the fractional part is discarded. If the value of the integral part cannot be represented by the long long int type, the result is the maximum value of the long long int type.
• When a value of long long int type is converted to floating type, if the value being converted is in the range of values that can be represented but cannot be represented exactly, the result is either the nearest higher or nearest lower value, depending on the IEEE rounding mode. You set the compile-time IEEE rounding mode with the -y compiler option.
• For binary operators that expect operands of arithmetic type, if either operand has type unsigned long long int, the other operand is converted to unsigned long long int. Otherwise, if either operand has type long long int, the other operand is converted to long long int.
• The maximum size of a bit-field remains 32-bit.
• A conversion specification may contain an optional ll, specifying that a following d, i, o, u, x, or X conversion specifier applies to a long long int or unsigned long long int argument.
• For power alignment rules, long long int identifiers and aggregates containing long long int members are aligned on a 64-bit boundary.
• For type-based aliasing, lvalues of type char, unsigned char, long long int, or unsigned long long int are considered as possible aliases of a long long int or unsigned long long int.
• The attribute listing will display long long integer for signed long long int identifiers and unsigned long long integer for long long int identifiers.
• In interlanguage calls, a C signed long long int maps to a Fortran INTEGER*8 and an unsigned long long int maps to a Fortran LOGICAL*8.

Other system limits are set in the /usr/include/sys/limits.h file. The limits.h header file is described in the Header Files Overview of the AIX Version 4 Files Reference.

Implementation-Defined Behavior
Implementation Dependencies
Type Conversions