The following table is a set of statements and keywords that can be used in the script.
Type | Description |
IF-ELSE Statement | Evaluates the expression after “If“. If the expression is true, then the code immediately following “If“ will be executed. Otherwise, the contents immediately following “Else“ will be executed. |
WHILE/DO-WHILE Statement | Statements for loop processes. |
FOR Statement | A statement for more complex loop processes. |
SWITCH-CASE Statement | Statement for executing different processes based on different conditions. |
GOTO Statement | A statement that forces the flow of program to go to a specific location in the script. |
CONTINUE Keyword | A keyword used in loop processes. |
RETURN Keyword | A keyword that designates the value that will be returned to the caller. |
RUNSCRIPT Keyword | A keyword that calls an external program. |
(1) IF-ELSE Statement
The IF-ELSE statement is one of the most frequently used logical decision-making statements. It supports nested IF statements such as: IF-ELSE IF-ELSE IF…. There is no limit on the level of nested IF. The Else statement may be omitted. The Else If statement is used for additional possible conditions following an If statement. For a given If-Else If-Else statement, only one branch will be executed. Once one condition is met, none of the other conditions are evaluated.
If (A == 1) { // A program for when A is 1 } Else If (A == 2) { // A program for when A is 2 } Else { // A program for when A is neither 1 nor 2 } |
(2) WHILE/DO-WHILE Statement
WHILE/DO-WHILE is a statement for a loop process. The statements below the while keyword will be repeated as long as the condition followed by the WHILE keyword is True.
A = 0; While (A<10) { // Write the program that will be repeated. // while the WHILE keyword’s condition is True. // This example will be repeated 10 times. A = A +1; } |
The subordinate statements may never be executed if the conditions for the WHILE statement are not true. If you use DO-WHILE statements, you can execute the loop statement at least once. Then the system will check the condition within the WHILE statement.
Do { // Write the loop statement when the condition is True. // The loop statement will be executed once at least. } While (A<10); // mark the end of the statement with ‘ ; ’. |
(3) FOR Statement
In this statement, all expressions for the initialization, the decision-making, and the post loop process are described in a single statement line.
The following example displays the WHILE statement example shown above but using the FOR statement instead.
For (A=0; A<10; A=A+1) { // Write the loop statement. } |
The FOR statement is followed by the initialization statement, the decision-making statement, and the post processing statement.
FOR (Initialization statement; Decision Making statement; Post Processing statement)
(4) SWITCH-CASE Statement
This statement is used when the different processes are needed within the different cases. Each case can be distinguished by the unlimited number of CASE statements.
The CASE keyword must be followed by a constant value and terminated with a colon “ : ”. Tags, variables, or expressions cannot be used in a CASE statement. Only one DEFAULT statement can be used in the SWITCH statement.
The DEFAULT statement does not need a constant. This statement is executed if none of the cases are to be executed. The DEFAULT statement can be omitted if needless.
The BREAK keyword plays the role of terminating the SWITCH statement. If there is no BREAK keyword in the process of the program, the corresponding CASE/DEFAULT statement will be executed.
Switch (A) { Case 1: // Write the program when A is 1. Break; Case 5: Case 7: // Write the program when A is 5 or 7. Break; Default: // Write the default program. This section can be omitted. Break; } |
(5) GOTO Statement
The GOTO statement controls the flow of the program directly. This statement uses an index (unique name starting with “@”) to point out the new location.
The index name must not be duplicated with variables, tags, or program names.
VAR A;
A = 0; @ComeHere // Assign an index. If (A < 10) { A = A + 1 Goto ComeHere; // Move to the assigned index. } |
(6) CONTINUE Keyword
The CONTINUE keyword is used in the loop statement. When the system meets the CONTINUE keyword, the flow moves to the first part of the current loop. This keyword is often used in the WHILE, DO-WHILE, and FOR statements. It is especially useful when there are multiple decision-making statements (IF-ELSE) in the loop.
The following examples operate identically.
While (A<10) { A = A +1; If (A < 5) { // Process when A is less than 5 } Else { // Process when A is greater than or equal to 5 } } |
While (A<10) { A = A +1; If (A < 5) { // Process when A is less than 5 Continue; } // Process when A is greater than or equal to 5 } |
(7) RETURN Keyword
Every program returns a result value to the caller. The RETURN keyword is used for designating a return value and termination of the program.
The following example processes three input parameters and returns the sum of them to the caller.
The name of the program shown below is MyPgm.
PARAM p1, p2, p3; Return p1+p2+p3; |
The program MyPgm will be called in the other program as shown below. Then the variable ‘RtnValue’ will receive the value ‘6’.
RtnValue = MyPgm(1, 2, 3); |
(8) RUNSCRIPT Keyword
When you call an external program directly, the caller will be in stand-by mode until the called program (the external program) ends its operation.
However, if you use RunScript keyword to call an external program, the caller will not wait until the end of the called program. Both the caller and called program will be executed in parallel.
If (A == 0) RunScript NewThread(); // Executes an external program (NewThread) A = A + 1; // Continues the rest of the program without stalling. |