Control statements

Control statements are used to modify 'code flow'. They allow code to conditionally be run, run multiple times, etc.

MCA currently has 3 control statements:

  • if/else - conditionally executes code
  • while/dowhile - executes code continuously while a condition is true
  • switch - executes different code based on different values

These are covered in more detail below.

if/else

The if statement allows code to be conditionally executed.

Structure

The if statement uses the following structure:

if (condition) {
    code
}

Where condition is an expression, and code is the code to be run if the condition evaluates to a truthy value (for more info on this, see the Types reference page).

Optionally, an else block can be added to the end. This block uses the following structure:

if (condition) {
    code
} else {
    else code
}

In this case, if condition evaluates to a falsey value, else code will be run instead of code. This is functionally the same as the following:

if (condition) {
    code
}
if (!condition) {
    else code
}

Best Practice: Always use else where possible instead of adding another if block with an inverted condition. The else block will execute faster, and also looks neater and is easier to understand.

while/dowhile

The while statement allows code to be executed multiple times.

Structure

The while statement uses the following structure:

while (condition) {
    code
}

Where condition is an expression, and code is the code to be run repedetively. code will be run while condition evaluates to a truthy value (for more info on this, see the Types reference page).

The while statement always runs the condition before the body. This means that the body might never be executed if the condition evaluates to false the first time.

Another, similar statement is the dowhile statement. Unlike while, dowhile executes the condition after the body. This means that the body will always be executed at least once. The dowhile statement has the following structure:

do {
    code
} while (condition);

switch

To do