Short Strings A ShortString is 0 to 255 characters long. While the length of a ShortString can change dynamically, its memory is
a statically allocated 256 bytes; the first byte stores the length of the string, and the remaining 255 bytes are available
for characters. If
S
is a ShortString variable,
Ord(S[0])
, like
Length(S)
, returns the length of
S
; assigning a value
to
S[0]
, like calling
SetLength
, changes the length of
S
. ShortString is maintained for backward compatibility only.
The Delphi language supports short-string types - in effect, subtypes of ShortString - whose maximum length is
anywhere from 0 to 255 characters. These are denoted by a bracketed numeral appended to the reserved word
string. For example,
var MyString: string[100];
creates a variable called
MyString
whose maximum length is 100 characters. This is equivalent to the declarations
type CString = string[100];
var MyString: CString;
Variables declared in this way allocate only as much memory as the type requires - that is, the specified maximum
length plus one byte. In our example,
MyString
uses 101 bytes, as compared to 256 bytes for a variable of the
predefined ShortString type.
When you assign a value to a short-string variable, the string is truncated if it exceeds the maximum length for the
type.
The standard functions High and Low operate on short-string type identifiers and variables. High returns the
maximum length of the short-string type, while Low returns zero.
