Datasheet

ARM Compiler Reference

3.3 C and C++ implementation details

This section describes implementation details for the ARM compilers, including:

• Character sets and identifiers

• Basic data types on page 3-23

• Operations on basic data types on page 3-24

• Structures, unions, enumerations, and bitfields on page 3-26.

3.3.1 Character sets and identifiers

The following points apply to the character sets and identifiers expected by the

compilers:

• Uppercase and lowercase characters are distinct in all internal and external

identifiers. An identifier can also contain a dollar

($)

character unless the

-strict

compiler option is specified.

• Calling

setlocale(LC_CTYPE, "ISO8859-1")

makes the

isupper()

and

islower()

functions behave as expected over the full 8-bit Latin-1 alphabet, rather than over

the 7-bit ASCII subset. The locale must be selected at link-time. (See Tailoring

locale and CTYPE on page 4-26.)

• The characters in the source character set are assumed to be ISO 8859-1 (Latin-1

Alphabet), a superset of the ASCII character set. The printable characters are

those in the range 32 to 126 and 160 to 255. Any printable character can appear

in a string or character constant, and in a comment.

• The ARM compilers do not support multibyte character sets, such as Unicode.

• Other properties of the source character set are host-specific.

The properties of the execution character set are target-specific. The ARM C and C++

libraries support the ISO 8859-1 (Latin-1 Alphabet) character set with the following

consequences:

• The execution character set is identical to the source character set.

• There are eight bits in a character in the execution character set.

• There are four characters (bytes) in an

int

. If the memory system is:

Little-endian The bytes are ordered from least significant at the lowest

address to most significant at the highest address.

Big-endian The bytes are ordered from least significant at the highest

address to most significant at the lowest address.