8-bit Data Types Integral data type

char signed byte range: -128...127

SignedByte signed byte range: -128...127

Byte unsigned byte range: 0...255

VHSelect unsigned char range: 0..1; v = 0, h = 1

Pascal String length prefix Byte, followed by up to 255 characters

Notes: In all cases where an 8-bit parameter is passed to the system, your

compiler must and will coerce it into a 16-bit value going in and back to an

8-bit value on the way out.

Signed data types cause automatic sign extension on conversion to larger

data types. Also comparisons works differently. For instance:

char theChar;

Byte theByte;

theInt = theChar; /* theInt becomes -1; ie, 0xFFFF */

theInt = theByte; /* theInt becomes 255; ie, 0x00FF */

Strings: Character Arrays

In this Guide and in all Macintosh references, a " string" refers to a

length-pre fixed, Pascal-style string; i.e., and array of up to 256 bytes

with the first byte indicating the length of the rest of the array. Other ways

to refer to a Pascal string include P string, p-string and (rarely) L string.

The Mac data types Str255, StringPtr, and StringHandle all assume a

length-prefixed array of 8-bit bytes. When passing the address of an

empty string, you may pass the address of a byte of 0, or (usually) just

pass 0 (NIL) as the address itself.

An ASCIIZ string is a common name for a standard C-language style array

of characters. It is composed of any number of 8-bit bytes, terminated by

a byte of 0. This may also be called a C- string.

The Mac system does not use ASCIIZ strings directly in any of its functions.

However, for many Stringxxx" function there is often a Textxxx

counterpart which works with unformatted text and requires a length

parameter ( obtainable via the C library call, strlen() ).

Be aware that as an array of chars, each element will be treated as a signed

entity. For instance:

doIt will be executed whenever the character has a value higher than 127

(signed chars larger than 127 are negative and get promoted to negative

integers).