Delphi Language Learning 4-Basic use of data types

1. Basic data types

1 delphi with some basic types of operation functions, such as Ord, PRED,SUCC, High,low

2) enumeration type

Declaration Type Suit = (club, Diamond, Heart, Spade)//where Ord (club) returns 0, ORD (Diamond) returns 1 ...

If the name of the enumerated type and the type name are used repeatedly:

Type Tsound = (Click, clack, Clock)
Procedure Tform1.dbgridenter (Sender:tobject);
var Thing:tsound;
Begin
   ...
   Thing: = Myunit.click;
End

Specifying the value of an enumeration type

Example 1
Type Size = (Small = 5, Medium = ten, Large = Small + Medium);
var x:size;
  X: = Small;    Ord (X) = 5
  Y: = Size (6);  Ord (X) = 6
  INC (X);        Ord (X) = 7
Example 2
Type Someenum = (e1, e2, E3 = 1)//ord (E1) returns 0, ORD (E2) returns 1, and Ord (E3) also returns 1;

3) Interval type (Subrange Types)

Declaration mode

Type
  Somenumbers = -128..127;
  Caps = ' A ' ... ' Z ';

2. Strings and characters

Convert string to uppercase

var I:integer;
Begin
   I: = Length (MyString);
   While I > 0 do
    Begin
       Mystring[i]: = Ansiuppercase (Mystring[i]);
       I: = I-1;
    End
End

String Assignment

MyString: = ' Hello world! ';
MyString: = ' Hello ' + ' world ';
MyString: = MyString + '! ';
MyString: = '; {Space}
MyString: = ';  {Empty string}

Short strings range 0 to 255

Using pointers

Const TEMPSTRING:ARRAY[0..12] of Char = ' Hello world! ';
var P:pchar;
   ...
P: = @TempString [0];