Declaration of variables - Rules for declaration of variables with examples - Variable Naming Convention

 

Declaration of variables - Rules for declaration of variables with examples 

Declaration of variables:

• A variable is a named storage location that can store a value of a particular data type.
• In other words, a variable has a name, a type and stores a value.
• In order to use a variable in C++, we must first declare it specifying which data type we want it to be.
• The syntax to declare a new variable is to write the specifier of the desired data type (like int, bool, float...) followed by a valid variable identifier.
• type nameOfTheVariable(identifier);

Examples:

• int number;
• float floatNumber;
• int firstNumber,  secondNumber,  thirdNumber;
• You can declare one variable in one statement .
• You could also declare many variables in one statement separating with commas (as in the third statement).

An identifier is needed to name a variable C++ imposes the following rules on identifiers: 

• An identifier is a sequence of characters, of up to a certain length (compiler-dependent, typically 255 characters), comprising uppercase and lowercase letters (a-z, A-Z), digits (0-9), and underscore "_".
• White space (blank, tab, new-line) and other special characters (such as +,-,*,/,@,&, commas, etc.) are not allowed.
• An identifier must begin with a letter or underscore. It cannot begin with a digit.  
• An identifier cannot be a reserved keyword or a reserved literal (e.g.,int,double,if,else,case,class,char,sizeof,for).
• Identifiers are case-sensitive. A rose is NOT a Rose, and is NOT a ROSE.

Variable Naming Convention:

A variable name is a noun, or a noun phrase made up of several words. The first word is in lowercase, while the remaining words are initial-capitalized, with no spaces between words. 

Examples: 

 firstNumber,leftNumber,xTopLeft and thisIsAVariableName.This convention is also known as camel-case