Declaration vs. Statement — What's the Difference?
Edited by Tayyaba Rehman — By Urooj Arif — Updated on April 16, 2024
A declaration in programming introduces and defines identifiers, like variables or functions, setting aside memory; a statement performs actions, such as assignments or loops.
Difference Between Declaration and Statement
Table of Contents
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Key Differences
A declaration in programming is used to introduce a new identifier, such as a variable or function, and optionally to define its initial value and type, while a statement is an executable unit of code that expresses an action to be carried out.
Declarations are foundational in specifying the data types and structure of the identifiers, making the code understandable to the compiler, whereas statements manipulate these identifiers to perform computations or control the flow of execution.
In some programming languages, a declaration can exist without immediately affecting the program's state, merely setting up the necessary framework for the identifiers, while statements directly influence the execution or state of the program from the moment they are run.
While declarations are primarily concerned with the introduction and setup of variables and functions within a scope, statements are the dynamic constructs that actually implement the logic and algorithms described by the program.
Declarations help in managing the program's memory use by allocating space for variables and defining the nature of functions, whereas statements often change the values stored in this memory or decide the direction of program flow based on conditions.
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Comparison Chart
Purpose
Introduces and defines identifiers.
Executes actions or controls flow.
Impact on Memory
Allocates and structures memory.
Uses and modifies memory content.
Example in C
Int number; (declares a variable)
Number = 5; (assigns a value)
Role in Execution
Non-executable, sets up framework.
Executable, performs operations.
Placement
Typically at the beginning of blocks.
Anywhere within blocks as needed.
Compare with Definitions
Declaration
A syntax used to introduce a new identifier with its type.
In C, int age; declares a variable named 'age' of type int.
Statement
Can alter the program's state or output.
Cout << Hello; outputs a string to the console.
Declaration
Necessary for type safety in statically typed languages.
Char letter; ensures 'letter' is used as a character.
Statement
Essential for the logic and flow of programs.
While (x < 10) { x++; } increments x until it is less than 10.
Declaration
Establishes the structure and scope of functions and variables.
Double calculate(double x); declares a function in C.
Statement
An executable unit of code that performs an action.
Return x + y; calculates the sum and returns it.
Declaration
Can optionally initialize the identifier at the time of declaration.
Int number = 10; declares and initializes 'number' to 10.
Statement
Often manipulates values defined by declarations.
X = 5; assigns the value 5 to the variable x.
Declaration
Helps in memory management by allocating space.
Float* ptr = new float; declares a pointer and allocates memory.
Statement
Includes control structures like loops and conditionals.
If (x > y) { return x; } checks and returns based on condition.
Declaration
A formal or explicit statement or announcement
A declaration of love
Statement
The act of stating or declaring
The attorney's statement took an hour.
Declaration
An act of declaring an innings closed.
Statement
Something stated; a declaration
The witness made many false statements.
Declaration
An explicit, formal announcement, either oral or written.
Statement
A formal oral or written declaration, especially with regard to facts or claims
In a statement, the firm denied any wrongdoing.
Declaration
The act or process of declaring.
Statement
An abstract of a commercial or financial account showing an amount due; a bill.
Declaration
A statement of taxable goods or of properties subject to duty.
Statement
A monthly report sent to a debtor or bank depositor.
Declaration
A formal statement initiating a lawsuit by specifying the facts and legal grounds for the relief sought; a complaint or petition.
Statement
(Computers) An elementary instruction in a programming language.
Declaration
An unsworn statement of facts that is admissible as evidence.
Statement
An overall impression or mood intended to be communicated, especially by means other than words
Glass, exposed beams, and antiques created a strong decorative statement.
Declaration
A bid, especially the final bid of a hand in certain card games.
Statement
Having a striking appearance, often because of large size, unusual design, or extensive ornamentation
A statement necklace.
Statement furniture.
Declaration
A meld.
Statement
A declaration or remark.
Make a statement
Publish a statement
Utter a statement
Declaration
A written or oral indication of a fact, opinion, intention, belief, etc.
A declaration of love
Statement
A presentation of opinion or position.
Declaration
A list of items for various legal purposes, e.g. customs declaration.
Statement
(finance) A document that summarizes financial activity.
A bank statement
Declaration
The act or process of declaring.
Statement
(computing) An instruction in a computer program, especially one that returns no value, as opposed to a function call.
Declaration
(cricket) The act, by the captain of a batting side, of declaring an innings closed.
Statement
(transitive) To provide an official document of a proposition, especially in the UK a Statement of Special Educational Needs.
Declaration
(legal) In common law, the formal document specifying plaintiff's cause of action, including the facts necessary to sustain a proper cause of action, and to advise the defendant of the grounds upon which he is being sued.
Statement
The act of stating, reciting, or presenting, orally or on paper; as, to interrupt a speaker in the statement of his case.
Declaration
(computing) The specification of an object, such as a variable or function, establishing its existence but not necessarily describing its contents.
Statement
That which is stated; a formal embodiment in language of facts or opinions; a narrative; a recital.
Declaration
The act of declaring, or publicly announcing; explicit asserting; undisguised token of a ground or side taken on any subject; proclamation; exposition; as, the declaration of an opinion; a declaration of war, etc.
Statement
A message that is stated or declared; a communication (oral or written) setting forth particulars or facts etc;
According to his statement he was in London on that day
Declaration
That which is declared or proclaimed; announcement; distinct statement; formal expression; avowal.
Declarations of mercy and love . . . in the Gospel.
Statement
A fact or assertion offered as evidence that something is true;
It was a strong argument that his hypothesis was true
Declaration
The document or instrument containing such statement or proclamation; as, the Declaration of Independence (now preserved in Washington).
In 1776 the Americans laid before Europe that noble Declaration, which ought to be hung up in the nursery of every king, and blazoned on the porch of every royal palace.
Statement
(music) the presentation of a musical theme;
The initial statement of the sonata
Declaration
A statement that is emphatic and explicit (spoken or written)
Statement
A nonverbal message;
A Cadillac makes a statement about who you are
His tantrums are a statement of his need for attention
Declaration
(law) unsworn statement that can be admitted in evidence in a legal transaction;
His declaration of innocence
Statement
The act of affirming or asserting or stating something
Declaration
A statement of taxable goods or of dutiable properties
Statement
(computer science) a line of code written as part of a computer program
Declaration
(contract bridge) the highest bid becomes the contract setting the number of tricks that the bidder must make
Statement
A document showing credits and debits
Declaration
A formal public statement;
The government made an announcement about changes in the drug war
A declaration of independence
Declaration
A formal expression by a meeting; agreed to by a vote
Common Curiosities
What is a declaration?
A declaration introduces an identifier and specifies its type.
Can a declaration also be a statement?
Yes, in languages like C, a declaration that initializes a variable can also be considered a statement.
Why are declarations important?
Declarations are crucial for type checking and memory allocation in statically typed languages.
What is an example of a statement that is not a declaration?
A loop like for (int i = 0; i < 10; i++) {} contains both a declaration and a statement but the loop control itself is a statement.
What is a statement?
A statement is an executable instruction that performs operations or controls execution flow.
How do statements affect a program?
Statements are the active parts of a program, directly affecting its operations and outputs.
Can you declare multiple identifiers at once?
Yes, languages like C and C++ allow multiple declarations in a single statement, e.g., int x, y, z;.
How do statements interact with memory?
Statements can modify memory by changing values of variables or manipulating data structures.
Is a function definition a declaration or a statement?
A function definition in languages like C and C++ is primarily a declaration.
What is the difference between a declarative and an imperative statement?
Declarative statements define what to do, often seen in SQL or functional programming, whereas imperative statements tell how to do something, typical in languages like Java or C.
Do all programming languages use declarations and statements?
Most programming languages use both, but the specifics and syntax may vary.
Can a single line contain both a declaration and a statement?
Yes, for example, int num = 5; declares and initializes num in one line.
Are there declarations that do not allocate memory?
Yes, declarations like function prototypes do not allocate memory but only define types and parameters.
Why might a programmer separate declarations from statements?
Separating them can enhance readability and maintainability by clearly distinguishing between setup and operational logic.
What are some common mistakes with declarations and statements?
Common mistakes include misplacing semicolons, type mismatches, or scope errors in declarations and logical errors in statements.
Can declarations affect program performance?
Incorrect or excessive declarations can lead to wasted memory, affecting performance.
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Written by
Urooj ArifUrooj is a skilled content writer at Ask Difference, known for her exceptional ability to simplify complex topics into engaging and informative content. With a passion for research and a flair for clear, concise writing, she consistently delivers articles that resonate with our diverse audience.
Edited by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
