Quick start manual

Syntactic elements 4-15
Expressions
Examples of set constructors:
[red, green, MyColor]
[1, 5, 10..K mod 12, 23]
['A
'..'Z', 'a'..'z', Chr(Digit + 48)]
For more information about sets, see “Sets” on page 5-18.
Indexes
Strings, arrays, array properties, and pointers to strings or arrays can be indexed. For
example, if FileName is a string variable, the expression FileName[3] returns the third
character in the string denoted by FileName, while FileName[I + 1] returns the
character immediately after the one indexed by I. For information about strings, see
“String types” on page 5-11. For information about arrays and array properties, see
“Arrays” on page 5-19 and “Array properties” on page 7-20.
Typecasts
It is sometimes useful to treat an expression as if it belonged to different type. A
typecast allows you to do this by, in effect, temporarily changing an expression’s
type. For example, Integer('A') casts the character A as an integer.
The syntax for a typecast is
typeIdentifier(expression)
If the expression is a variable, the result is called a variable typecast; otherwise, the
result is a value typecast. While their syntax is the same, different rules apply to the
two kinds of typecast.
Value typecasts
In a value typecast, the type identifier and the cast expression must both be ordinal or
pointer types. Examples of value typecasts include
Integer('A')
Char(48)
Boolean(0)
Color(2)
Longint(@Buffer)
The resulting value is obtained by converting the expression in parentheses. This
may involve truncation or extension if the size of the specified type differs from that
of the expression. The expression’s sign is always preserved.
The statement
I := Integer('A');
assigns the value of Integer('A'), which is 65, to the variable I.
A value typecast cannot be followed by qualifiers and cannot appear on the left side
of an assignment statement.