Loop

Introduction

In the Wave language, loops are provided to allow repeated execution of code. Loops are used to repeatedly execute code while a certain condition is met or a specific number of times.

The following loops are supported in Wave:

• while loop: condition-based repetition

• for loop: count-based repetition

In addition, keywords such as break and continue are provided to control the flow in the middle of loops. This section explains how to use loops and flow control keywords.

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while loop

The while loop repeatedly executes a block of code as long as the given condition evaluates to true. The loop terminates when the condition becomes false.

Basic Structure

Here is the basic syntax for a while loop:

while (condition) {
    // code to repeat
}

• The condition must be of boolean type.

• The code block is enclosed in {} and can contain one or more statements.

Example: Print numbers from 0 to 4

var i :i32 = 0;

while (i < 5) {
    println("i is {}.", i);
    i = i + 1;
}

In this example, the loop repeats until i is less than 5, prints the value each time, and increments by 1.

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for loop

The for loop is useful when the number of iterations is predetermined. The loop is constructed by specifying the initial value, termination condition, and increment/decrement expression.

Basic Structure

for (var variableName: type = initialValue; condition; increment/decrement) {
    // code to repeat
}

• Variable name: the variable used for loop control

• Condition: the loop executes as long as it is true

• Increment/Decrement: changes the value of the loop variable

Example: Print numbers from 1 to 5

for (var i: i32 = 1; i <= 5; i = i + 1) {
    println("i = {}", i);
}

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Nested Loops

You can write another loop inside a loop, which is called nested loops. This is useful for iterating over structures like 2D arrays or combinations.

Example: Double while loop

var i :i32 = 0;

while (i < 3) {
    var j :i32 = 0;

    while (j < 2) {
        println("i={}, j={}", i, j);
        j = j + 1;
    }

    i = i + 1;
}

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break Statement

The break statement immediately exits the loop and jumps outside. It is useful for halting a loop when a specific condition is met.

Example: Exit loop at a specific value

var i :i32 = 0;

while (true) {
    if (i == 5) {
        break;
    }

    println(i);
    i = i + 1;
}

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continue Statement

The continue statement skips the rest of the current loop iteration and begins the next one. It is used when you want to execute only part of the loop block under certain conditions.

Example: Print only even numbers

for (var i: i32 = 0; i <= 10; i = i + 1) {
    if (i % 2 == 1) {
        continue;
    }

    println(i);
}

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Summary

Syntax	Description
while	Loops while a condition is true.
for	Executes loops with initial value, condition, and increment expression.
break	Immediately exits loop.
continue	Skips to the next loop.

Loops in Wave are designed for coherent handling of condition-based or count-based repeat operations.

Using break and continue statements allows for more precise loop flow control.