Structure vs. Union: Know the Difference
By Shumaila Saeed || Updated on December 25, 2023
A structure in programming allocates separate memory for each of its members, while a union uses the same memory location for all its members.
Key Differences
In programming, a structure is a data type that allows the storage of different data types under one name. Each member within a structure has its own memory location. A union, on the other hand, also stores different data types but uses a single shared memory location for all its members, storing only one member at a time.
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Nov 18, 2023
The size of a structure is determined by the total sum of the sizes of its members. It represents the total memory required to store all members. In contrast, the size of a union is determined by the size of its largest member, as it can only hold one member at a time in the shared memory space.
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When a structure is used, accessing each member is independent of the others as each has a unique memory location. This allows for different members to be accessed and modified simultaneously. In a union, since all members share the same memory location, modifying one member can alter the values of others.
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Structures are typically used when storing multiple distinct data items that need to be accessed independently, such as different attributes of an object. Unions are useful in situations where only one of several data items is required at a time, allowing for memory-efficient storage.
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In summary, structures offer a way to group different data types with independent memory allocations for each member, providing flexibility and independent access. Unions, while similar in syntax, focus on memory efficiency by overlapping the storage of its members, suitable for specialized use cases where only one member is used at a time.
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Nov 18, 2023
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Comparison Chart
Memory Allocation
Allocates separate memory for each member.
Shares the same memory location for all members.
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Size Determination
Size equals the sum of all member sizes.
Size equals the size of the largest member.
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Member Accessibility
Independent access to each member.
Only one member can be used at a time.
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Usage Scenario
For storing multiple distinct data items.
For storing one of several data items at a time.
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Modification Impact
Modifying one member does not affect others.
Modifying one member can alter others.
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Structure and Union Definitions
Structure
An arrangement or organization of parts to form an object.
The Eiffel Tower is known for its intricate metal structure.
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Union
The act of being united or joined.
The union of these two companies will create a market leader.
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Structure
A complex system considered from the point of view of the whole rather than of any single part.
The social structure of the community was very inclusive.
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Union
In programming, a data type allowing the storage of different data types in the same memory location.
We used a union to efficiently manage memory in our software.
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Structure
The quality of being organized.
She admired the structure of the well-planned garden.
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Structure
The way in which parts are arranged or put together to form a whole.
The structure of the novel was unique and engaging.
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Union
A combination so formed, especially an alliance or confederation of people, parties, or political entities for mutual interest or benefit.
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Structure
Something made up of a number of parts that are held or put together in a particular way
Hierarchical social structure.
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Union
(Mathematics) A set, every member of which is an element of one or another of two or more given sets.
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Structure
The way in which parts are arranged or put together to form a whole; makeup
Triangular in structure.
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Union
Agreement or harmony resulting from the uniting of individuals; concord.
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Structure
The interrelation or arrangement of parts in a complex entity
Political structure.
Plot structure.
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Union
The state of matrimony; marriage
"The element that was to make possible such a union was trust in each other's love" (Kate Chopin).
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Structure
The arrangement or formation of the tissues, organs, or other parts of an organism.
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Union
A combination of parishes for joint administration of relief for the poor in Great Britain.
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Structure
To give form or arrangement to
Structure a curriculum.
Structure one's day.
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Structure
A cohesive whole built up of distinct parts.
The birds had built an amazing structure out of sticks and various discarded items.
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Structure
The underlying shape of a solid.
He studied the structure of her face.
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Union
A device on a flag or ensign, occupying the upper inner corner or the entire field, that signifies the union of two or more sovereignties.
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Structure
The overall form or organization of something.
The structure of a sentence.
The structure of the society was still a mystery.
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Union
An organization at a college or university that provides facilities for recreation; a student union.
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Structure
A set of rules defining behaviour.
For some, the structure of school life was oppressive.
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Structure
(computing) Several pieces of data treated as a unit.
This structure contains both date and timezone information.
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Union
Union The United States of America regarded as a national unit, especially during the Civil War.
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Structure
Underwater terrain or objects (such as a dead tree or a submerged car) that tend to attract fish
There's lots of structure to be fished along the west shore of the lake; the impoundment submerged a town there when it was built.
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Union
Union Of, relating to, or loyal to the United States of America during the Civil War
A Union soldier.
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Structure
A body, such as a political party, with a cohesive purpose or outlook.
The South African leader went off to consult with the structures.
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Union
Of or relating to a labor union or labor union organizing
The union movement.
Union negotiations.
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Structure
(logic) A set along with a collection of finitary functions and relations.
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Union
(countable) The act of uniting or joining two or more things into one.
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Structure
(transitive) To give structure to; to arrange.
I'm trying to structure my time better so I'm not always late.
I've structured the deal to limit the amount of money we can lose.
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Union
(countable) The state of being united or joined; a state of unity or harmony.
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Structure
The act of building; the practice of erecting buildings; construction.
His son builds on, and never is contentTill the last farthing is in structure spent.
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Union
(countable) That which is united, or made one; something formed by a combination or coalition of parts or members; a confederation; a consolidated body; a league.
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Structure
Manner of building; form; make; construction.
Want of insight into the structure and constitution of the terraqueous globe.
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Structure
Arrangement of parts, of organs, or of constituent particles, in a substance or body; as, the structure of a rock or a mineral; the structure of a sentence.
It [basalt] has often a prismatic structure.
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Union
(countable) An association of students at a university for social and/or political purposes; also in some cases a debating body.
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Structure
Manner of organization; the arrangement of the different tissues or parts of animal and vegetable organisms; as, organic structure, or the structure of animals and plants; cellular structure.
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Union
(countable) A joint or other connection uniting parts of machinery, such as pipes.
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Structure
That which is built; a building; esp., a building of some size or magnificence; an edifice.
There stands a structure of majestic frame.
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Structure
A thing constructed; a complex construction or entity;
The structure consisted of a series of arches
She wore her hair in an amazing construction of whirls and ribbons
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Structure
The manner of construction of something and the arrangement of its parts;
Artists must study the structure of the human body
The structure of the benzene molecule
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Structure
The complex composition of knowledge as elements and their combinations;
His lectures have no structure
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Union
A data structure that can store any of various types of item, but only one at a time.
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Structure
A particular complex anatomical structure;
He has good bone structure
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Structure
The people in a society considered as a system organized by a characteristic pattern of relationships;
The social organization of England and America is very different
Sociologists have studied the changing structure of the family
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Union
(historical) An affiliation of several parishes for joint support and management of their poor; also the jointly-owned workhouse.
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Structure
In programming, a data structure consisting of a group of elements.
We used a structure to store various data types in our code.
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Union
Belonging to, represented by, or otherwise pertaining to a labour union.
Actors have to be union to get work here.
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Union
The act of uniting or joining two or more things into one, or the state of being united or joined; junction; coalition; combination.
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Union
Agreement and conjunction of mind, spirit, will, affections, or the like; harmony; concord.
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Union
That which is united, or made one; something formed by a combination or coalition of parts or members; a confederation; a consolidated body; a league; as, the weavers have formed a union; trades unions have become very numerous; the United States of America are often called the Union.
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Union
A textile fabric composed of two or more materials, as cotton, silk, wool, etc., woven together.
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Union
A large, fine pearl.
If they [pearls] be white, great, round, smooth, and weighty . . . our dainties and delicates here at Rome . . . call them unions, as a man would say "singular," and by themselves alone.
In the cup an union shall he throw,Richer than that which four successive kingsIn Denmark's crown have worn.
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Union
A device emblematic of union, used on a national flag or ensign, sometimes, as in the military standard of Great Britain, covering the whole field; sometimes, as in the flag of the United States, and the English naval and marine flag, occupying the upper inner corner, the rest of the flag being called the fly. Also, a flag having such a device; especially, the flag of Great Britain.
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Union
A joint or other connection uniting parts of machinery, or the like, as the elastic pipe of a tender connecting it with the feed pipe of a locomotive engine; especially, a pipe fitting for connecting pipes, or pipes and fittings, in such a way as to facilitate disconnection.
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Union
A cask suspended on trunnions, in which fermentation is carried on.
One kingdom, joy, and union without end.
[Man] is to . . . begetLike of his like, his image multiplied.In unity defective; which requiresCollateral love, and dearest amity.
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Union
An organization of employees formed to bargain with the employer;
You have to join the union in order to get a job
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Union
The United States (especially the northern states during the American Civil War);
He has visited every state in the Union
Lee hoped to detach Maryland from the Union
The North's superior resources turned the scale
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Union
The act of pairing a male and female for reproductive purposes;
The casual couplings of adolescents
The mating of some species occurs only in the spring
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Union
The state of being joined or united or linked;
There is strength in union
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Union
The state of being a married couple voluntarily joined for life (or until divorce);
A long and happy marriage
God bless this union
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Union
Healing process involving the growing together of the edges of a wound or the growing together of broken bones
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Union
A political unit formed from previously independent people or organizations;
The Soviet Union
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Union
A set containing all and only the members of two or more given sets;
Let C be the union of the sets A and B
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Union
The occurrence of a uniting of separate parts;
Lightning produced an unusual union of the metals
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Union
A device on a national flag emblematic of the union of two or more sovereignties (typically in the upper inner corner)
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Union
The act of making or becoming a single unit;
The union of opposing factions
He looked forward to the unification of his family for the holidays
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Union
Being of or having to do with the northern United States and those loyal to the Union during the Civil War;
Union soldiers
Federal forces
A Federal infantryman
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Union
Of trade unions;
The union movement
Union negotiations
A union-shop clause in the contract
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Union
The act of joining two or more things into one.
The union of the two rivers created a beautiful delta.
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Union
A state of harmony or agreement.
They were in union on the decision to move forward.
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Union
An organized association of workers formed to protect and further their rights and interests.
The workers formed a union to negotiate better terms.
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Repeatedly Asked Queries
What is the primary use of a union in programming?
A union is primarily used to save memory by efficiently storing one of several data types at a time.
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Nov 18, 2023
How does a union differ from a structure in terms of memory?
A union uses the same memory location for all its members, unlike a structure which allocates separate memory for each member.
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What happens when you modify a member of a union?
Modifying a member of a union can change the values of other members since they share memory space.
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What is the main advantage of using a union?
The main advantage of using a union is its memory efficiency, as it uses the same memory for different members.
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Can a structure contain multiple data types?
Yes, a structure can contain multiple data types, each as a separate member.
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What is a structure in programming?
A structure is a user-defined data type in programming that groups different data types under one name.
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How is the size of a structure determined?
The size of a structure is the sum of the sizes of all its members.
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Can unions have methods in programming?
No, unions in programming are used for storage and don't have methods.
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Is it possible for a union and a structure to have the same members?
Yes, both can have the same types of members, but they handle them differently in memory.
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Can structures be nested in programming?
Yes, structures can be nested within other structures.
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Are structures in programming similar to classes?
Structures are similar to classes but lack features like methods and access specifiers.
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How does memory alignment work in structures?
In structures, each member is aligned in memory according to its data type.
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What distinguishes a structure's functionality from a union's?
A structure allows independent access and storage of multiple data types, while a union focuses on memory efficiency by overlapping these data types.
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What is a typical scenario for using a structure?
Structures are typically used when there is a need to group different data types and access them independently.
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What is the impact of modifying a structure's member?
Modifying a member of a structure does not affect the other members.
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How is the size of a union calculated?
The size of a union is determined by its largest member.
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Are arrays allowed in structures?
Yes, arrays can be used as members of structures.
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Can a union contain a structure?
Yes, a union can contain a structure as one of its members.
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Can a union be used to store different data types simultaneously?
No, a union can only store one data type at a time in its shared memory space.
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Is it possible to initialize a structure at the time of declaration?
Yes, structures can be initialized at the time of declaration in programming.
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Nov 18, 2023
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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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