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Difference Between Identifier and Variable

IdentifierThe word ‘identifier’ clearly defines itself; an identifier is a name given to an entity, which distinctly identifies an entity in a program at the time of its execution. Variable is also an identifier; its name uniquely identifies itself in a program.

Here, the fundamental difference between an identifier and variable is that an identifier is a “name given to entity” in a program whereas, a variable is a “name given to memory location”, that is used to hold value, which may get modified during program execution.

Furthermore, the name given to a variable, function, class, structure, that is in the source code of the program is an identifier. As against, a variable is a name associated with the memory cell whose value can be altered in a program. The number of characters can be more in the identifier as compared to a variable.

Content: Identifier Vs Variable

  1. Comparison Chart
  2. Definition
  3. Key Differences
  4. Conclusion

Comparison Chart

Basis for ComparisonIdentifierVariable
UseIdentifier is used to name a variable, function, class, structure, union etc.Variable is used to name a memory location, which holds a value.
PurposeCreated to give a unique name to an entity.Allots a unique name to a particular memory location.
RangeAll identifiers are not variable.All variables names are identifier.
Exampleint a;
or
int a(){
//
}
int a;
or
float a;
//

Definition of Identifier

The name we use to call a particular entity in a program, which is not a keyword is called “identifier“. Identifier particularly names a ‘variable, function, structure, enum, class etc’. An identifier distinctly identifies an entity in a program while its execution. Two identifiers cannot have the same name in a program.

Example

Let’s understand it with an example.

float area;

Here ‘float’ is a ‘keyword’, and ‘area’ is an ‘identifier’. The identifier ‘area’ is a name given to a ‘variable’ which will store a float value. Now if ‘area’ weren’t a variable, but a function, then

float area(){
}

Here, ‘area’ is still an identifier, but this time, the identifier ‘area’ is a name given to a ‘function’. We have discussed the rules for naming an identifier in our previous article difference between keyword and identifier; you can go through it to understand it in a better way.

Definition of Variable

Variable is a “name given to a distinct memory location”. This named memory location contains a value which may be modified while the program gets executed. In C, a variable must be declared at the beginning of a program whereas, in C++, a variable could be declared anywhere in a program.

Types of Variables

Variables can be ‘local’, ‘global’ or ‘reference’ .

  • Local variables are declared inside a function
  • Global variables are declared outside a function.
  • Reference variables are those which provide an “alternate name” for the previously defined variable.

If a variable is referenced to another variable, both the variables can be used alternately to represent that variable. If a variable accepts the value of an argument in a function, these variables are called ‘formal parameter’.

Rules for creating a Variable

  • It can contain any combination of the alphabets, digits or underscores.
  • Some compilers permit only variable having the length up to 247 characters. However, programmers prefer to use up to 31 characters length for a variable as this is convenient for them.
  • The initial character of a variable name should be an alphabet or underscore as it is an identifier some of the rules are similar.
  • Use of commas and blanks is not permitted within a variable name.
  • None of the special symbols except ‘underscore’ can be used in a variable name.

Variablenew

Declaration of a variable

//type vaiable_name;
int add;

A list of variables of the same type can be created at an instance, separated by a comma.

//type variable_list;
int a, b, c;

In C++ variables could be initialized at runtime; it is referred to as ‘dynamic initialization’.

Example

float area = 3.14*rad*rad;

This statement would initialize the variable ‘area’ at runtime.

Key Differences Between Identifier and Variable

  1. Both an identifier and a variable are the names allotted by users to a particular entity in a program. The identifier is only used to identify an entity uniquely in a program at the time of execution. On the contrary, a variable is a name given to a memory location, that is used to hold a value.
  2. Variable is only a kind of identifier; other kinds of identifiers are function names, class names, structure names, etcetera. So it can be said that all variables are identifiers whereas, vice versa is not true.
  3. The number of characters in an identifier can be greater than that of a variable.

Conclusion

As identifier and variable names are user-defined names, it should be taken care that no two identifiers or no two variable names in a program should be the same. It will create a problem of ambiguity in a program.

Related Differences:

  1. Difference Between Keyword and Identifier
  2. Difference Between Float and Double
  3. Difference Between Strong and Weak Entity
  4. Difference Between Single and Multiple Inheritance
  5. Difference Between Structure and Union

Comments

  1. Harshi says

    May 22, 2018 at 3:18 pm

    Useful one

    Reply
  2. Balaji T says

    December 15, 2018 at 6:51 am

    Thanks a lot, and Very useful information.

    Reply
  3. Deus says

    December 11, 2022 at 7:10 am

    Very well understood,am beginner

    Reply

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