From Clomosy Docs
This page contains commonly used keywords and directives in the programming language. Keywords form the fundamental building blocks of a programming language and are used to perform specific tasks. Acting as commands, these words manage the control flow, data structures, and other essential operations within a program. The correct use of keywords during programming is crucial for building error-free and efficient code.
Below is a list of the main keywords used in the programming language. Understanding these keywords will help you grasp the structure of the language and use the correct syntax when developing software.
NOTE: A keyword should not be used as a variable name.
Begin
The Begin keyword is used in the Clomosy platform within the BASE Syntax to start expression blocks. This type of block is used at the beginning of the main block in your code and within conditions, loops, procedures, and function structures.
Example:
var
valueStr : String;
Begin
for i := 1 to 10 do
Begin
ShowMessage('Number: '+IntToStr(i));
end;
end;
End
The End keyword is used in the Clomosy platform within the BASE Syntax to terminate expression blocks. This type of block is used at the end of the main block in your code and within conditions, loops, procedures, and function structures.
Example:
var
i : Integer;
begin
i := 2;
case i of
0 : Showmessage('i = 0');
1 : Showmessage('i = 1');
2 : Showmessage('i = 2');
End;
End;
var
The var keyword is used for defining variables. To create a variable, var is used to specify the name and type of the variable. This keyword allocates memory in the program to store a specific data type.
Example:
TRObject Syntax
Var
appName : String;
year : Integer;
{
appName = 'Clomosy';
year = 2023;
ShowMessage('appName = '+appName );
ShowMessage('Year = '+IntToStr(year));
}
Base Syntax
Var
appName : String;
year : Integer;
begin
appName := 'Clomosy';
year := 2023;
ShowMessage('appName = '+appName );
ShowMessage('Year = '+IntToStr(year));
end;
And
The and keyword is used as a logical operator in the BASE syntax structure of the Clomosy platform. It is used to combine two or more conditions and returns a true value only when all conditions are true. In other words, if all expressions combined with and are true, the result is true; otherwise, it is false.
The And keyword is used in two different ways:
1. To perform a logical or boolean 'and' of two logical values. If both are true, then the result is true, otherwise, the result is false.
2. To perform a mathematical 'and' of two integers. The result is a bitwise 'and' of the two numbers. For example:
10110001 And 01100110 = 00100000
Example
var
num1, num2, num3 : Integer;
letter : Char;
begin
num1 := $25;
num2 := $10;
letter := 'G';
if (num1 > 0) And (letter = 'G')
then ShowMessage('Both values are true')
else ShowMessage('None or only one true value');
num3 := num1 And num2;
ShowMessage('25 And 32 = '+ IntToStr(num3));
end;
Or
It is used as a logical operator. It combines two or more conditions to check if at least one of them is true. If at least one of the conditions combined with or is true, the result is true; otherwise, the result is false.
Example
TRObject Syntax
var
num1, num2, num3 : Integer;
letter : Char;
begin
num1 := $25;
num2 := $10;
letter := 'G';
if (num1 > 0) Or (letter = 'G')
then ShowMessage('Both values are true')
else ShowMessage('None or only one true value');
num3 := num1 Or num2;
ShowMessage('25 And 32 = '+ IntToStr(num3));
end;
Xor
As a logical operator, xor combines two or more conditions and checks whether only one of them is true. If only one of the conditions combined with xor is true, the result will be true; however, if both conditions are true or both are false, the result will be false. This operator is useful for expressing the logic of "either one or the other" between conditions.
Example
var
num1, num2, num3 : Integer;
letter : Char;
begin
num1 := $25;
num2 := $10;
letter := 'G';
if (num1 > 0) Xor (letter = 'G')
then ShowMessage('Both values are true')
else ShowMessage('None or only one true value');
num3 := num1 Xor num2;
ShowMessage('25 And 32 = '+ IntToStr(num3));
end;
Not
It is used as a logical operator to negate a condition; that is, the not operator evaluates a condition as false if it is true, and as true if it is false. This way, it is useful for altering the logical states of conditions.
Example
TRObject Syntax
var
num1, num2 : Word;
{
num1 = $2C; // Binary value : 0000 0000 0010 1100
// Not'ed value : 1111 1111 1101 0011 = $FFD3
// And used to return a Boolean value
if Not (num1 > 0)
ShowMessage('num1 <= 0')
else ShowMessage('num1 > 0');
// And used to perform a mathematical NOT operation
num2 = Not num1;
// Display the result
ShowMessage('Not $2C = $'+IntToHex(num2,2));
}
Base Syntax
var
num1, num2 : Word;
begin
num1 := $2C; // Binary value : 0000 0000 0010 1100
// Not'ed value : 1111 1111 1101 0011 = $FFD3
// And used to return a Boolean value
if Not (num1 > 0)
then ShowMessage('num1 <= 0')
else ShowMessage('num1 > 0');
// And used to perform a mathematical NOT operation
num2 := Not num1;
// Display the result
ShowMessage('Not $2C = $'+IntToHex(num2,2));
end;
Array
The Array provides single and multi dimensional arrays (indexable sequences) of data. Dynamic arrays have no preallocated storage. When defined, only a pointer is created. For detailed information, visit the page.
As
The as keyword is used for type casting. It is particularly useful in object-oriented programming when a object needs to be converted from one type to another. This operation should only be performed between compatible types; otherwise, an error will occur.
Case
The Case keyword provides a structured equivalent to a sequence of if statements on the same variable. The case statement is more elegant, more efficient, and easier to maintain than multiple if nestings.The brief definition is as follows.
Example
TRObject Syntax
var
day: Integer;
dayName: String;
{
day = 3; // Example day number
case day of
{
1: dayName = 'Monday';
2: dayName = 'Tuesday';
3: dayName = 'Wednesday';
4: dayName = 'Thursday';
5: dayName = 'Friday';
6: dayName = 'Saturday';
7: dayName = 'Sunday';
else
dayName = 'Invalid day'; // If the given day number is not between 1-7
}
ShowMessage('Day: ' + dayName);
}
Base Syntax
var
day: Integer;
dayName: String;
begin
day := 3; // Example day number
case day of
1: dayName := 'Monday';
2: dayName := 'Tuesday';
3: dayName := 'Wednesday';
4: dayName := 'Thursday';
5: dayName := 'Friday';
6: dayName := 'Saturday';
7: dayName := 'Sunday';
else
dayName := 'Invalid day'; // If the given day number is not between 1-7
end;
ShowMessage('Day: ' + dayName);
end;
Const
The const keyword is used to define constant values. Constants are values that remain unchanged during the execution of the program. A constant defined with const takes a value of a specific type, and this value cannot be altered after its declaration. This feature enhances the reliability and readability of the code.
const
pi = 3.14;
Div
The Div keyword gives the whole number result of dividing the Dividend by the Divisor. Any remainder is discarded.
Dividend div divisor
For detailed information, see the page.
Do
The Do keyword is always a part of one of the shown 3(with - for - while)control types. It precedes the Statements section of the control action.
Example
with for;
With AddImg do begin
Height := 70;
Align := alRight;
Margins.Right:=50;
end;
for for loop;
for j := beginning to finish do
begin
//lines of code
end;
while for;
while first<=end do //if the situation is true
begin
//lines of code
end;
downto
The DownTo keyword prefixes the target value Expression in a For loop. The DownTo expression maybe an Integer, Character or Enumeration type.
See the For keyword for full details. The examples illustrate the three expression types.
1 for Variable := Integer Expression downto Integer Expression do Statement; 2 for Variable := Char Expression downto Char Expression do Statement; 3 for Variable := Enum Expression downto Enum Expression do Statement;
for j := beginning downto finish do
begin
//lines of code
end;
else
The Else keyword is part of the If, Case and Try statements. It is used to start the section of code executed when earlier conditions are not satisfied. See details of each of these statements for further details.
(for, case)
- 1 keyword Else(if Condition then Statement else Statement;
- 2 case Expression of
- Case clauses
- ...
- else
- Statements
- end;
- Case clauses
- 3 try
- Statements
- ...
- except
- Exception statements
- ...
- else
- Statements
- end
- Statements
Try
The Try keyword is used to mark the start of a block of statements that have error trapping. If an error occurs, the program is not terminated. Instead, control is passed to either a Finally or Except section.
For example:
var
number, zero : Integer;
begin
number := -1;
Try
zero := 0;
number := 1 div zero;
ShowMessage('number / zero = '+IntToStr(number));
finally
ShowMessage('Number was not assigned a value - using default');
end;
end;
except
The Except keyword is used to mark the start of a block of statements that handle an exception in a Try clause. If the Except block can handle the exception, then the program is not terminated.
try .... .... code to be executed under normal conditions. ... .. except ... .. code to be executed under normal circumstances, and code to be executed when an exception occurs during the execution of the normal code. .. . end;
Example:
var
number, zero : Integer;
begin
// Try to divide an integer by zero - to raise an exception
Try
zero := 0;
number := 1 div zero;
ShowMessage('number / zero = '+IntToStr(number));
Except
ShowMessage('Unknown error encountered');
end;
end;
finally
The Finally keyword is used to mark the start of the final block of statements in a Try statement. They are executed regardless of what happens in the Try statements. However, the Finally clause does not actually handle any exceptions - the program will terminate if no Except clause is found (see notes below).
Try-Finally is normally used by a routine to allow cleanup processing to take place, such as freeing resources, with the exception being correctly passed to the caller to handle.
try .... .... code to be executed under normal conditions. ... .. finally ... .. Commands to be executed no matter what .. . end;
Example:
var
number, zero : Integer;
begin
// Try to divide an integer by zero - to raise an exception
number := -1;
Try
zero := 0;
number := 1 div zero;
ShowMessage('number / zero = '+IntToStr(number));
Finally
if number = -1 then
begin
ShowMessage('Number was not assigned a value - using default');
number := 0;
end;
end;
end;
Output: Number was not assigned a value - using default
Then, the program terminates with an not division by zero when evaluating runtime error message - the finally clause did not trap the error.
If you want it to work without errors, change the value of the zero variable.
Repeat
The Repeat keyword starts a control loop that is always executed at least once, and which terminates when the Expression is satisfied (returns True).
There is no need for Begin or End markers - the Repeat and Until keywords serve that purpose.
It is used when it is important that the statements are at least executed once.
Until
The Until keyword ends a control loop that is always executed at least once, and which terminates when the Expression is satisfied (returns True).
There is no need for Begin or End markers - the Repeat and Until keywords serve that purpose.
It is used when it is important that the statements are at least executed once.
for
The For keyword starts a control loop, which is executed a finite number of times.
The Variable is set to the result of the 1st Expression. If the result is less than or equal to the result of the 2nd Expression (when to is specified), then the Statement is executed. Variable is then incremented by 1 and the process is repeated until the variable value exceeds the 2nd expression value.
For downto, the variable value is checked as being greater than or equal to the 2nd expression, and its value is decremented at the loop end. The Statement maybe a single line, or a set of statements with a begin/end block.
Example:
var
i : Integer;
begin
// Loop 5 times
For i := 1 to (10 div 2) do
ShowMessage('i = '+IntToStr(i));
end;
while
The While keyword starts a control loop that is executed as long as the Expression is satisfied (returns True).
The loop is not executed at all if the expression is false at the start.
You need Begin or End markers if multiple statements are required in the loop. See the While keyword for full details.
with
The With keyword is a convenience provided by Clomosy for referencing elements of a complex variable, such as a record or object.
It simplifies the code by removing the need to prefix each referenced element with the complex variable name. See the With keyword for full details.
to
The To keyword prefixes the target value Expression in a For loop. The To expression maybe an Integer, Character or Enumeration type. See the For keyword for full details.
Function
The Function keyword defines a subroutine that returns a value. See the SubRoutines tutorial for details on using functions. See page for detailed information.
Procedure
The Procedure keyword defines a subroutine that does not return a value. See the Procedure tutorial for details on using procedures.
if
The If keyword is used to control the flow of code depending on the logical result of the given condition. See page for detailed information.
then
The Then keyword is part of the If statement. It is used to start the section of code executed when the if condition is true.See the if keyword for full details.
mod
The Mod keyword gives the remainder from dividing the Dividend by the Divisor. The whole number result of the division is ignored. See page for detailed information.