Flow control statements

Control statements are:

IF/THEN/ELSE, WHILE/BREAK/CONTINUE, RETURN

IF statement

The IF statement allows conditional execution based on the evaluation of an expression. IF statements can be nested.

Syntax:

IF (condition) true-statements [ ELSE false-statements] ;

Table 1. If Statement

Part	Description
IF	The keyword to begin the control structure.
Condition	A numeric or string expression that evaluates true (one) or false (zero).
True-statements	Statement(s) performed when the condition is true.
ELSE	(Optional) Keyword to begin the False control flow.
False-statements	Statement(s) performed if the condition is false.

Multiple statements are permitted as part of the true-statements or false-statements. If multiple statements are to be executed, they must appear within a statement block embedded within braces { }. Example:

If (userid != "") setField(userid,1,5); 
If (userid != "") setField (userid,1,5) 
else 
errMsg("Userid must be specified"); 
If ( op == 5 ) 
{ setField(userid,1,5);   
sendKey("Enter"); 
} 
else  
if (op == 3)  
setField(pswd,2,5); 
else 
msgBox("unknown operation:); 
if (prompt("enter Name") == "") errMsg("Name must be specified");

For statement

The For statement allows iterative execution based on the evaluation of an expression. An initializer statement can be executed to establish initial conditions. A conditional expression is used to control the number of times the loop is executed. An update statement is issued each iteration through the loop.

Syntax:

FOR (initial-statement ; condition ; update-statement ) loop-statements ;

Table 2. For Statement

Part	Description
For	The keyword to begin the loop control structure.
Initial-statement	A statement to be executed prior to the loop.
Condition	A numeric or string expression that evaluates true (one) or false (zero). A function that returns an integer result. The loop continues to execute while this condition is true.
Update-statement	A statement that will be executed at the end of each iteration.
Loop-statements	Statement(s) performed when the condition is true.

Multiple statements are permitted as part of the loop-statements. If multiple statements are to be executed, they must appear within a statement block embedded in braces { }. Example:

For ( i=0; i<3; i=I+1) waitforscreen(1000); 
For ( i=0; i<3; i=i+1) 
{    
sendString(userid);    
if (waitforstring ("Logon complete") > 0)    
{    
success = true;    
break;;    
} 
}

Return statement

Use the Return statement to return from a function or to end the main program block. Program execution resumes at the statement following the point at which a function was called, or exits the script if it is in the main program block. An optional value can be associated with the return statement.

A RETURN statement that is not within a function definition terminates the script.

Syntax:

RETURN [return-value];

Table 3. Return Statement

Part	Description
RETURN	The keyword to pass control to the calling statements.
return-value	An optional value to be returned to the caller. This can be a constant value, literal, or expression.

Example:

..... 
return 0;

While statement

The While statement executes a series of statements in a loop for as long as a condition is true.

Syntax:

WHILE (expression) statements;

Table 4. While Statement

Part	Description
While	The keyword to begin the control structure.
Condition	A numeric or string expression that evaluates true (one) or false (zero).
statements	Statement(s) performed while the condition true.

Example:

cnt = 1;   
WHILE (cnt < 3)  
{   
a = a+1;  
cnt = cnt + 1; 
} 
// this will execute the loop 3 times

Break statement

The Break statement causes control to exit a While loop regardless of the condition controlling the loop.

Syntax:

BREAK;

Example:

cnt= 1; 
WHILE (cnt < 3)  
{   
userid = prompt("Enter Userid");   
if (logon(userid) == 1) break;   
cnt = cnt + 1; 
}

Continue statement

The Continue statement causes the execution of the While loop to resume at the top, without executing the rest of the statements in the block.

Syntax:

Continue;

Example:

cnt= 1;      
WHILE (cnt < 3)       
{        
userid = prompt("Enter Userid");        
if (logon(prompt("Enter Userid")) != 1)        
{        
msgBox("Invalid Logon id");        
continue;        
};        
// do other logic....        
}