Quick start manual

Data types, variables, and constants

5-5

Simple types

When you increment the last value or decrement the first value of an integer type, the

result wraps around the beginning or end of the range. For example, the Shortint type

has the range –128..127; hence, after execution of the code

var I: Shortint;

I := High(Shortint);

I := I + 1;

the value of I is –128. If compiler range-checking is enabled, however, this code

generates a runtime error.

Character types

The fundamental character types are AnsiChar and WideChar. AnsiChar values are

byte-sized (8-bit) characters ordered according to the locale character set which is

possibly multibyte. AnsiChar was originally modeled after the ANSI character set

(thus its name) but has now been broadened to refer to the current locale character

set.

WideChar characters use more than one byte to represent every character. In the

current implementations, WideChar is word-sized (16-bit) characters ordered

according to the Unicode character set (note that it could be longer in future

implementations). The first 256 Unicode characters correspond to the ANSI

characters.

Note

On Linux, wchar_t widechar is 32 bits per character. The 16-bit Unicode standard

that Delphi WideChars support is a subset of the 32-bit UCS standard supported by

Linux and the GNU libraries. Delphi WideChar data must be widened to 32 bits per

character before it can be passed to an OS function as wchar_t.

The generic character type is Char, which is equivalent to AnsiChar. Because the

implementation of Char is subject to change, it’s a good idea to use the standard

function SizeOf rather than a hard-coded constant when writing programs that may

need to handle characters of different sizes.

A string constant of length 1, such as 'A', can denote a character value. The

predefined function Chr returns the character value for any integer in the range of

AnsiChar or WideChar; for example, Chr(65) returns the letter A.

Character values, like integers, wrap around when decremented or incremented past

the beginning or end of their range (unless range-checking is enabled). For example,

after execution of the code

var

Letter: Char;

I: Integer;

begin

Letter := High(Letter);

for I := 1 to 66 do

Inc(Letter);

end;

Letter has the value A (ASCII 65).