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