Control Statements

Some statements serve to control the processing flow.

All control statements can be grouped into the following categories:

• Conditional Statements

• Iteration Statements

• Jump Statements

• Try-Catch Statement

Conditional Statements

These statements serve to perform different set of statements depending on condition value.

If Statement

On the basis of the Condition value, this statement decides whether the Statement should be executed. If the Condition is true, the Statement is executed. If it is false, the Statement is ignored and the process continues next after the if statement. The Statement is either a simple statement or a block of statements:

if (Condition) Statement

Unlike the previous version of the if statement (in which the Statement is executed only if the Condition is true), other Statements that should be executed even if the Condition value is false can be added to the if statement. Thus, if the Condition is true, the Statement1 is executed, if it is false, the Statement2 is executed. See below:

if (Condition) Statement1 else Statement2

The Statement2can even be another if statement, and also with an else branch:

if (Condition1) Statement1
    else if (Condition2) Statement3
        else Statement4

Example 72. If statement

integer a = 123;
if ( a < 0 ) {
    a = -a;
    }

Switch Statement

Sometimes you would have very complicated statement if you created the statement of more branched out if statement. In this case, it is much more convenient to use the switch statement.

Now, instead of the Condition as in the if statement with only two values (true or false), an Expression is evaluated and its value is compared with the Constants specified in the switch statement.

Only the Constant that equals to the value of the Expression decides which of the Statements is executed.

If the Expression value is Constant1, the Statement1 will be executed, etc.

Remember that literals must be unique in the Switch statement.

switch(Expression) {
    case Constant1 : Statement1 StatementA [break;]
    case Constant2 : Statement2 StatementB [break;]
    ...
    case ConstantN : StatementN StatementW [break;]
}

The optional break; statements ensure that only the statements corresponding to a constant will be executed. Otherwise, all below them would be executed as well.

In the following case, even if the value of the Expression does not equal the values of the Constant1,…​,ConstantN, the default statement (StatementN+1) is executed.

switch (Expression) {
    case Constant1 : Statement1 StatementA [break;]
    case Constant2 : Statement2 StatementB [break;]
    ...
    case ConstantN : StatementN StatementW [break;]
    default : StatementN+1 StatementZ
}

Example 73. Switch statement

integer ok = 0;
switch ( response ) {
    case "yes":
    case "ok":
        a = 1;
        break;
    case "no":
        a = 0;
        break;
    default:
        a = -1;
}

Iteration Statements

Iteration statements repeat some processes during which some inner Statements are executed repeatedly until the Condition that limits the execution cycle becomes false or they are executed for all values of the same data type.

For Loop

Firstly, the Initialization is set up. Secondly, the Condition is evaluated and if its value is true, the Statement is executed. Finally, the Iteration is made.

During the next cycle of the loop, the Condition is evaluated again and if it is true, Statement is executed and Iteration is made. This way the process repeats until the Condition becomes false. Then the loop is terminated and the process continues with the other part of the program.

If the Condition is false at the beginning, the process jumps over the Statement out of the loop.

for (Initialization;Condition;Iteration)
    Statement

Remember that the Initialization part of the For Loop may also contain the declaration of the variable that is used in the loop. Initialization, Condition and Iteration are optional.

Example 74. For loop

integer result = 1;
integer limit = 5;
for(integer i = 1; i <= limit; ++i) {
    result = result * i;
}

Do-While Loop

Firstly, the Statement is executed. Secondly, the value of the Condition is evaluated. If its value is true, the Statement is executed again and then the Condition is evaluated again and the loop either continues (if it is true again) or stops and jumps to the next or higher level subprocesses (if it is false).

Since the Condition is at the end of the loop, even if it is false at the beginning of the subprocess, the Statement is executed at least once.

do Statement while (Condition)

integer a = 5;
integer sum = 0;
do {
    sum = sum + a;
    a--;
} while (a > 3);

While Loop

The processing depends on the value of the Condition. If its value is true, the Statements is executed and then the Conditionis evaluated again and the processing either continues (if it is true again) or stops and jumps to the statement following the cycle (if it is false).

Since the Conditionis at the beginning of the loop, if it is false before entrance to the loop, the Statements is not executed at all and the loop is jumped over.

while (Condition) Statement

integer a = 5;
integer sum = 0;
while ( a > 3 ) {
    sum = sum + a;
    a--;

For-Each Loop

The foreach statement is executed on all fields of the same data type within a container. Its syntax is as follows:

foreach (<data type> myVariable : iterableVariable) Statement

All elements of the same data type (data type is declared in this statement) are searched in the iterableVariable container. The iterableVariable can be a list, map, record or variant. For each variable of the same data type, specified Statement is executed. It can be either a simple statement or a block of statements.

Thus, for example, the same Statement can be executed for all string fields of a record, etc.

It is possible to iterate over values of a map (i.e. not whole <entries>). The type of the loop variable has to match the type of map’s values:

map[string, integer] myMap = {'first' -> 1, 'second' -> 2};
foreach(integer value: myMap) {
    printErr(value); // prints 1 and 2
}

To obtain map’s keys as a list[], use the getKeys() function.

When iterating over a variant (if it contains a list, map or a record), use variant as the loop control variable type: foreach (variant v: …​)

variant myVariant = [1, 'hello', true, today()];
foreach(variant value: myVariant ) {
    printErr(value); // 1, 'hello', true and actual date
}

Jump Statements

Sometimes you need to control the process in a different way than by decision based on the Condition value. To do that, you have the following options:

Break Statement

If you want to jump out of a loop or of a switch, you can use the following statement in the program:

break;

The processing of a loop (or switch) is relinquished and it continues with Statements following the loop or switch.

Continue Statement

If you want to stop processing of some iteration and go to next one, you can use the following statement in the program:

continue;

The processing jumps to the end of a loop, iteration is performed (in for loop) and the processing continues with next iteration step.

Return Statement

In the functions, you can use the return word either alone or along with an expression. (See the following two options below.)

The return statement can be in any place within the function. There may also be multiple return statements among which a specific one is executed depending on a condition, etc.

return;

return expression;