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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
[Important]Important

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 59.21. 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 Condition is 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 Condition is 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 or a record. 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.

[Note]Note

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

	map[string, integer] myMap;

    myMap["first"] = 1;
    myMap["second"] = 2;            	

    foreach(integer value: myMap) {
        printErr(value); // prints 1 and 2
    }

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

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