Curly braces (also referred to as just "braces" or as "curly brackets") are a major part of the C++ programming language. They are used in several different constructs, outlined below, and this can sometimes be confusing for beginners.

An opening curly brace { must always be followed by a closing curly brace }. This is a condition that is often referred to as the braces being balanced. The Arduino IDE (Integrated Development Environment) includes a convenient feature to check the balance of curly braces. Just select a brace, or even click the insertion point immediately following a brace, and its logical companion will be highlighted.

Beginner programmers, and programmers coming to C++ from the BASIC language often find using braces confusing or daunting. After all, the same curly braces replace the RETURN statement in a subroutine (function), the ENDIF statement in a conditional and the NEXT statement in a FOR loop.

Unbalanced braces can often lead to cryptic, impenetrable compiler errors that can sometimes be hard to track down in a large program. Because of their varied usages, braces are also incredibly important to the syntax of a program and moving a brace one or two lines will often dramatically affect the meaning of a program.

Example Code

The main uses of curly braces are listed in the examples below.


void myfunction(datatype argument) { // any statement(s) }


while (boolean expression) { // any statement(s) } do { // any statement(s) } while (boolean expression); for (initialisation; termination condition; incrementing expr) { // any statement(s) }

Conditional Statements

if (boolean expression) { // any statement(s) } else if (boolean expression) { // any statement(s) } else { // any statement(s) }

See Also


Arduino UNO R3
Arduino Starter Kit
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