Keyword vs. Identifier: Know the Difference
By Shumaila Saeed || Published on February 11, 2024
Keywords are reserved words in a programming language with a fixed meaning, whereas identifiers are names created by programmers for variables, functions, etc.
Key Differences
Keywords in programming languages are predefined, reserved words that have special meanings already attached to them. These meanings are integral to the functionality of the language and cannot be altered. Identifiers, on the other hand, are the names given by programmers to various programming elements like variables, functions, classes, etc. Unlike keywords, identifiers can be chosen freely by the programmer and are not predefined.
Shumaila Saeed
Feb 11, 2024
Each keyword in a programming language serves a specific purpose and is part of the language's syntax. For example, 'if', 'while', 'class', and 'return' are common keywords in many languages. These cannot be used as identifiers because their meanings and functions are fixed. Identifiers, in contrast, are user-defined and hold no meaning until they are assigned one within the program. They serve as a reference to the data they represent.
Shumaila Saeed
Feb 11, 2024
The syntax of a programming language often dictates certain rules for creating identifiers, such as not allowing them to start with a number or use special characters. However, within these rules, programmers have the freedom to create any identifier. Keywords, due to their fixed nature, do not follow such flexibility. They are a finite set of words that the programming language understands and processes in a particular way.
Shumaila Saeed
Feb 11, 2024
In programming, the understanding and correct use of keywords is essential for the language to interpret the code correctly. Misuse of keywords can lead to syntax errors. Identifiers, while crucial for code readability and maintainability, do not carry the same level of syntactic significance. An incorrectly named identifier might lead to confusion but not necessarily a syntax error.
Shumaila Saeed
Feb 11, 2024
Finally, keywords often dictate the structure and flow of a program. For instance, loop keywords like 'for' and 'while' determine how many times certain actions are performed. Identifiers, while they name and reference various elements in a program, do not have control over the program's structure. Their primary role is to make the code understandable and manageable.
Shumaila Saeed
Feb 11, 2024
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Comparison Chart
Definition
A reserved word in a language.
A name given to a programming entity.
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Feb 11, 2024
Purpose
Integral to language syntax and structure.
Names variables, functions, etc., for clarity.
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Feb 11, 2024
Rules
Has fixed rules defined by the language.
Follows naming conventions, but more flexible.
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Feb 11, 2024
Role in Code
Controls program flow and structure.
References and labels code elements.
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Feb 11, 2024
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Keyword and Identifier Definitions
Keyword
A reserved word in programming with a specific, unchangeable meaning.
In Python, def is a keyword used to define a function.
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Jan 25, 2024
Identifier
A symbolic name adhering to certain rules in a programming language.
TotalCost in a program is an identifier for storing a calculated value.
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Jan 25, 2024
Keyword
A word that forms the core vocabulary of a programming language.
The if keyword in many languages is used to introduce a conditional statement.
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Jan 25, 2024
Identifier
An alphanumeric name used to identify various programming entities.
In float interestRate = 0.05;, interestRate is an identifier for a floating-point variable.
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Jan 25, 2024
Keyword
A pre-defined term that is syntactically important in code.
Return in C++ specifies what a function should return.
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Identifier
A programmer-chosen word used to reference specific parts of code.
UserAccount can be an identifier for a class in object-oriented programming.
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Keyword
A word that cannot be used as an identifier due to its reserved status.
In Java, class is a keyword used to declare a class.
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Jan 25, 2024
Identifier
A name given by programmers to elements like variables, functions, or classes.
In int age = 25;, age is an identifier for an integer variable.
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Jan 25, 2024
Keyword
An integral part of a programming language's syntax.
While is a keyword used for looping in many programming languages.
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Jan 25, 2024
Identifier
To establish or recognize the identity of; ascertain as a certain person or thing
Can you identify what kind of plane that is? I identified the man at the next table as a famous actor.
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Identifier
(Biology) To determine the taxonomic classification of (an organism).
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Identifier
To ascertain as having a certain characteristic or feature
Job candidates who are identified as overqualified.
Children who have been identified with hearing loss.
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Keyword
A word used as a reference point for finding other words or information.
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Identifier
To consider as identical or united; equate
The Greek god Ares is identified with the Roman god Mars.
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Identifier
To associate or affiliate closely with
Writers who are identified with modernism.
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Keyword
(information science) Any word#Noun used in a reference work to link to other words or other information.
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Identifier
To consider oneself as sharing certain characteristics or attitudes as another
She identifies strongly with her grandmother.
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Keyword
(information science) Any important word#Noun in a text#Noun or document, which may be linked to other words or other information, or at least merely listed in the metadata for searches to find.
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Identifier
To associate oneself with or admire something, such as a set of ideas
A language learner who identifies with a new culture.
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Keyword
(programming) A reserved word used to identify a specific command, function, etc.
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Identifier
To believe or assert that one belongs to a certain group or class
She identifies as a libertarian. He identifies as bisexual.
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Keyword
(linguistics) Any word that occurs in a text more often than normal.
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Identifier
Someone who identifies; a person who establishes the identity of someone or something.
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Keyword
(transitive) To tag with keywords, as for example to facilitate searching.
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Identifier
Something that identifies or uniquely points to something or someone else.
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Keyword
A word used as an entry point into an index which serves to identify files, records, texts, or other data containing the key or some related word, such as a synonym. It is a type of key{15}; as, a boolean combination of keywords is more effective for information retrieval than a single key{15}.
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Identifier
One who identifies as a particular type or role; one who says and believes that they are a certain thing.
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Identifier
A guidebook that helps determine the specific class of an object (such as a mushroom, herb, fish, bird, drug, or mineral), or its individual identity (such as that of a star).
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Jan 24, 2024
Identifier
A formal name used in source code to refer to a variable, function, procedure, package, etc. or in an operating system to refer to a process, user, group, etc.
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Jan 24, 2024
Identifier
(HTML) A code that distinguishes a particular element from all other elements in a document.
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Identifier
A user-defined label for various code components.
CalculateSum() is an identifier for a function in many programming languages.
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Repeatedly Asked Queries
Can a keyword be used as an identifier?
No, keywords cannot be used as identifiers as they have predefined meanings in a programming language.
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Feb 11, 2024
How many keywords are there in a programming language?
The number of keywords varies by programming language, typically ranging from 20 to 70.
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Feb 11, 2024
Can an identifier be renamed?
Yes, identifiers can be renamed as long as the new name adheres to the language's naming conventions.
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Are there any reserved identifiers?
Yes, some names are reserved in certain contexts or programming languages, though they are not keywords.
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Feb 11, 2024
Can an identifier be a single character?
Yes, identifiers can be as short as a single character, though longer, descriptive names are encouraged for clarity.
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Feb 11, 2024
Can identifiers contain numbers?
Yes, identifiers can contain numbers, but they typically cannot start with a number.
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Feb 11, 2024
Are identifiers case-sensitive?
Yes, in most programming languages, identifiers are case-sensitive.
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Feb 11, 2024
Can an identifier start with an underscore?
In many languages, yes, an identifier can start with an underscore.
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Feb 11, 2024
Is it a good practice to use meaningful identifiers?
Yes, meaningful identifiers make code more readable and maintainable.
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Feb 11, 2024
Can keywords be abbreviated or shortened?
No, keywords must be used as they are defined in the language.
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Feb 11, 2024
Are keywords universal across all programming languages?
No, different programming languages have different sets of keywords.
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Feb 11, 2024
Do keywords have a semantic meaning in the code?
Yes, keywords have specific semantic meanings and roles in the programming language.
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Feb 11, 2024
Do all programming languages have the same keywords?
No, each programming language has its own set of keywords.
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Feb 11, 2024
Are there conventions for naming identifiers?
Yes, different programming languages often have conventions, such as camelCase or snake_case.
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Feb 11, 2024
Are keywords always lowercase?
In most languages, keywords are lowercase, but this can vary.
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Feb 11, 2024
Can identifiers contain special characters?
Typically, identifiers cannot contain special characters, with the exception of the underscore.
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Feb 11, 2024
Can two identifiers have the same name in the same scope?
No, identifiers must be unique within their scope.
Shumaila Saeed
Feb 11, 2024
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About Author
Written by
Shumaila SaeedShumaila Saeed, an expert content creator with 6 years of experience, specializes in distilling complex topics into easily digestible comparisons, shining a light on the nuances that both inform and educate readers with clarity and accuracy.
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