Pascal essential notes
There is an exception to the case where the PASCAL language is not sensitive: the Register process in the control package must begin with uppercase letter R because it is necessary to be compatible with C Builder.
The compiler does not compile the space in the code, the empty line, and Tab key spaces, which are generally called blank, which is only used to improve the readability of the code, which does not affect the compilation process. (That is, = this way of writing is no problem, I originally thought that it is the problem!)
Remember to use code template (easy to develop) shortcuts: Ctrl J
Absolute keywords are shared variable addresses with some icons of C . Var str: string [32]; strlen: Byte Absolute Str; BYTE ABSOLUTE STR;
In contrast to most programming languages, the priority of the And and OR operators in the Pascal language is higher than the relationship operator. Therefore, if your code is a
Collection, set in addition to and ( ) difference (-) ration (*), etc., can be used in both incrude and Exclude efficiency
INCLUDE (Style, Fsbold);
When the time and date are converted into a string, its conversion format depends on Windows system settings.
Round conversion a real value is the integer value of rounding
Note: In the most recent version of the Delphi Pascal compiler, the Round function is based on the CPU's FPU (floating point component) processor. This processor uses a so-called "Bank Home Relievance", that is, when implementing the Round function of the intermediate value (such as 5.5, 6.5), the processor determines the rounding or not, according to the odd plurality of the digital, even the number of numbers, such as 5.5 The result is 6, and the 6.5 Round result is also 6 because 6 is even. Not just Delphi (VB is like this)
Note: In general, you should avoid using the above-mentioned non-named types because you can't transfer them as a parameter, and you cannot use other variables that are named the same type. In fact, PASCAL's type compatibility rules are based on type name instead of the actual type definition. The same variables of two types may still be incompatible unless their types have exactly the same name. For non-named types, the compiler is required to assign an internal name, so the complicated variables for the data structure are used to define the named data type, you will not be a white feet.
Delphi compiles, but when running, if you open the range check compilation option (in the Compiler page settings of the Engineering Options dialog), you will get the Range Check Error information.
Note: It is recommended that you turn on the above-described compile option when developing programs to make the program more robust and easy to debug. This way, even if you encounter an error, you will get a clear information rather than difficult to ponder. You can remove this option when you finalize the program, so that the program is running fast, but it has little effect. So I suggest that you open all runtime detection options, such as overflow checks and stack checks, or even submit them when you submit procedures.
The Delphi long string is slightly different, and the long string looks like a reference, but if you change the string variable of the string, then this string will be copied before the update. A long string that is transmitted as a value is only reference only in terms of memory usage and operation speed, but if you change the value of the string, the initial value will not be affected. Conversely, if the long string is transmitted by reference, the initial value of the string can be changed. The value of substantially string is similar to reference, but the system is operated behind the scenes, which is low.
It is not often used in Delphi, but you often use an extremely similar structure-reference (References). Each object instance is actually an implicit pointer, or is a reference to its actual data. Using reference, you can use object variables like other data types.
When the parameter is passed by reference, the reference parameter is labeled keyword VAR.
Procedure Doublethevalue (VARUE: Integer);
Delphi 3 adds a new parameter: OUT. The OUT parameter does not have an initial value, just used to return a value. OUT parameters should only be used for COM processes and functions, in general, preferably use more efficient VAR parameters. In addition to this, the OUT parameter is the same as the VAR parameters except for the initial value.
Constant parameters, unable to change the passed value in the process or function. Can only be used.
If you only pass a part of the array, you can use the SLICE function,
Ming a process or function, and only give its name and parameters, do not list the current code, need to add Forward key in the sentence:
Key words table
Keyword
effect
Absolute
Directive (variable)
Abstract
Directive (method)
and
Operator (Boole)
array
Types of
AS
Operator (RTTI)
ASM
Statement
Assembler
Backward compatibility (assembly)
AT
Statement (exception handling)
Automated
Access class (class)
Begin
Block mark
Case
Statement
CDECL
Function call protocol
Class
Types of
Const
Declaration or instructions (parameters)
Constructor
Special method
Contains
Operator (collection)
DEFAULT
Directive (attribute)
Destructor
Special method
Dispid
Dispinterface interface category
DISPINTERFACE
Types of
Div
Operator
DO
Statement
Downto
Statement (for)
Dynamic
Directive (method)
Else
Statement (IF or CASE)
end
Block mark
Except
Statement (exception handling)
Export
Backward compatibility (class)
Exports
statement
EXTERNAL
Directive (function)
FAR
Backward compatibility (class)
File
Types of
Finalization
Unit structure
Finally
Statement (exception handling)
for
Statement
Forward
Function instruction
FUNCTION
statement
goto
Statement
IF
Statement
IMPLEMentation
Unit structure
IMPLEMENTS
Directive (attribute)
in
Operator (collection) - engineering structure
Index
DIPINTERFACE interface)
inherited
Statement
INITIALIZATION
Unit structure
inline
Backward compatibility (see ASM)
Interface
Types of
IS
Operator (RTTI)
label
statement
Library
Program structure
Message
Directive (method)
MOD
Operator (mathematics)
Name
Directive (function)
Near
Backward compatibility (class)
NIL
Numerical value
Nodefault
Directive (attribute)
NOT
Operator (Boole)
Object
Backward compatibility (class)
Of
Statement (CASE)
on
Statement (exception handling)
oral
Operator (Boole)
OUT
Directive (parameter)
Overload
Function instruction
Override
Function instruction
Package
Program structure (control package)
packed
Directive (record)
Pascal
Function call protocol
Private
Access class (Class)
Procedure
statement
PROGRAM
Program structure
Property
statement
protected
Access class (class)
public
Access class (class)
Published
Access class (class)
Raise
Statement (exception handling)
reta
Attribute category
Readonly
Dispatch interface category
Record
Types of
Register
Function call protocol
Reintroduce
Function instruction
Repeat
Statement
Requires
Program structure (control package)
Resident
Directive (function)
ResourceString
Types of
SafeCall
Function call protocol
set
Types of
SHL
Operator (mathematics)
SHR
Operator (mathematics)
Stdcall
Function call protocol
stored
Directive (attribute)
String
Types of
THEN
Statement (IF)
Threadvar
statement
TO
Statement (for)
Try
Statement (exception handling)
Type
statement
Unit
Unit structure
Until
Statement
Uses
Unit structure
VAR
statement
Virtual
Directive (method)
While
Statement
WITH
Statement
Write
Attribute category
Writeonly
Dispatch interface category
xor
Operator (Boole)
Operator priority table
Single operator (highest priority)
@
Take the address of variables or functions (return a pointer)
NOT
Logical reckless or pressing
Ride and bit position operators
*
Multiplication or collection
/
Floating point
Div
Integer
MOD
Taking the mold (the remainder of the integer)
AS
Program Running Phase Type Conversion (RTTI Operator)
and
Logic or pressing and
SHL
Displacement
SHR
Press-to-right shift
Add or subtract operator
Add, set, set, string connection, or pointer add an offset
-
Simble, set difference set or pointer to reduce an offset
oral
Logic or standing or operation
xor
Logic or component differentiation or operation
Relationship and comparison operator (minimum priority)
=
Determine if it is equal
<>
Determine if it is not equal
<
Determine if it is less than
>
Is it greater than
<=
Determine if it is less than or equal to, or is a set of subsets
> =
Determine if it is greater than or equal to, or is a collection of parent
in
Judging whether it is a collection member
IS
Judging whether the object is type compatible (another RTTI operator)
