Identifiers in C++ Language Tutorials with Program Example

Identifiers in C++ is a variable, function, class, module, or any other user-defined item object that can be identified by its name in C++, starting with a letter from A to Z, a to Z, or an underscore character is used as the first character of an identifier. One or more letters, digits 0, underscores, or numbers are then added (0 to 9).

The punctuation letters @, $, and percent are not permitted in C++ identifiers. Identifiers are case-sensitive distinctions in a programming language that is important in C++. Consequently, in C++, man and manpower are two separate identifiers.

These are the general guidelines for variable naming:

• Numerals, letters, and underscores can all be used in names.
• To start a name, use a letter or an underscore (_).
• Case affects names only (myVar and myvar are different variables).
• Whitespace and special characters like!, #, percent, etc., are not permitted in names.
• Names cannot contain reserved terms (such as C++ keywords like int).

If we adhere to the guidelines above, we are free to select any name as an identifier. However, we ought to provide an identifier that makes sense with significant names.

Good and Bad Identifier Examples

Invalid Identifiers	Bad Identifier	Good Identifier
Total points	T_points	totalPoint
1list	list_1	list1
float	n_float	floatNumber

C++ Keywords

The reserved words that have a particular significance to the compiler are known as keywords. They cannot be used as identifiers since they are reserved for a specific application.

For instance, the predefined terms “for,” “break,” “while,” “if,” and “else” are words whose meaning has already been determined by the compiler.

The names a programmer assigns to program elements to identify a variable, functions, arrays, objects, and classes are known as identifiers.

All C++ keywords are listed below.

alignas	decltype	namespace	struct
alignof	default	new	switch
and	delete	noexcept	template
and_eq	do	not	this
asm	double	not_eq	thread_local
auto	dynamic_cast	nullptr	throw
bitand	else	operator	true
bitor	enum	or	try
bool	explicit	or_eq	typedef
break	export	private	typeid
case	extern	protected	typename
catch	false	public	union
char	float	register	unsigned
char16_t	for	reinterpret_cast	using
char32_t	friend	return	virtual
class	goto	short	void
compl	if	signed	volatile
const	inline	sizeof	wchar_t
constexpr	int	static	while
const_cast	long	static_assert	xor
continue	mutable	static_cast	xor_eq

Related Articles

• C++ Syntax: What is the Basic Syntax of C++?

Conclusion

We learned What is an identifier in C++, which can be used as a variable, constant, function name, or user datatype variable, a mix of numbers, letters, and underscores(_), starting with a letter or underscore. All identifiers must go by a few restrictions to be recognized by the compiler; otherwise, an error will be raised. Additionally, an identifier cannot be one of the keywords defined in C++ libraries.