Loops

While loops

In a while loop, you execute a certain block of code while a condition is true. The syntax is as follows:

while(condition) {
    // block of code
    // to be executed
}

The example below counts from 1 to 10:

i = 1;
while(i <= 10) {
    Console.print(i);
    i = i + 1;
}

For loops

A for loop is a more controlled repetition structure when compared to the while loop. For loops support an initialization command, a condition and an increment command. The syntax is as follows:

for(initialization; condition; increment) {
    // block of code
    // to be executed
}

The code just displayed is equivalent to:

initialization;
while(condition) {
    // block of code
    // to be executed

    increment;
}

The example below counts from 1 to 10:

for(i = 1; i <= 10; i++) {
    Console.print(i);
}

Foreach

Foreach loops are used to iterate throughout iterable collections (such as Arrays and Dictionaries). Basically: for each element x in the iterable collection, do something with x. The syntax is as follows:

foreach(element in collection) {
    // block of code
    // to be executed
}

The example below counts from 1 to 10:

collection = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
foreach(x in collection) {
    Console.print(x);
}

The example below iterates over a Dictionary:

dictionary = { "a": 1, "b": 2, "c": 3 };
foreach(entry in dictionary) {
    Console.print(entry.key);
    Console.print(entry.value);
}

Implementing your own iterable collections

The foreach loop can be used with any iterable collections, not only Arrays and Dictionaries. You may even implement your own!