What is the difference between struct and class in terms of access modifier

Online GK. How do we declare an abstract class? Which of the following is not a valid conditional inclusions in preprocessor directives. Which looping process checks the test condition at the end of the loop? Which of the following keyword supports dynamic method resolution? A direct access file is:. Which of the following is not true about preprocessor directives.

Which of the following functions below can be used Allocate space for array in memory? What is the implicit pointer that is passed as the first argument for nonstatic member functions? As a rule of thumb, the majority of types in a framework should be classes. There are, however, some situations in which the characteristics of a value type make it more appropriate to use structs. If you are after a video explaining all the differences, you can check out Part 29 - C Tutorial - Difference between classes and structs in C.

Instances of classes are stored on the managed heap. All variables 'containing' an instance are simply a reference to the instance on the heap. Passing an object to a method results in a copy of the reference being passed, not the object itself. Structures technically, value types are stored wherever they are used, much like a primitive type. The contents may be copied by the runtime at any time and without invoking a customised copy-constructor.

Passing a value type to a method involves copying the entire value, again without invoking any customisable code. The keywords "class" and "struct" as used by C are simply something that must be learned. To add to the other answers, there is one fundamental difference that is worth noting, and that is how the data is stored within arrays as this can have a major effect on performance. With an array of classes, the values you're interested in are not stored within the array, but elsewhere in memory.

For a vast majority of applications this difference doesn't really matter, however, in high performance code this will affect locality of data within memory and have a large impact on the performance of the CPU cache.

The slowest thing a modern CPU does is not crunching numbers, it's fetching data from memory, and an L1 cache hit is many times faster than reading data from RAM. Here's some code you can test. A structure is a value type so it is stored on the stack, but a class is a reference type and is stored on the heap. By default, all the struct members are public but class members are by default private in nature.

As a structure is a value type, we can't assign null to a struct object, but it is not the case for a class. Well, for starters, a struct is passed by value rather than by reference.

Structs are good for relatively simple data structures, while classes have a lot more flexibility from an architectural point of view via polymorphism and inheritance. Others can probably give you more detail than I, but I use structs when the structure that I am going for is simple. Just to make it complete, there is another difference when using the Equals method, which is inherited by all classes and structures. So , structures are suited for numeric-like objects, like points save x and y coordinates.

And classes are suited for others. Even if 2 people have same name, height, weight A lock this for a struct would not work since you can only lock on a reference type expression. Creating a struct instance cannot cause a garbage collection unless the constructor directly or indirectly creates a reference type instance whereas creating a reference type instance can cause garbage collection.

This means that a struct is always instantiable whereas a class might not be since all its constructors could be private. A struct cannot have a destructor. A destructor is just an override of object. Finalize in disguise, and structs, being value types, are not subject to garbage collection.

A struct is implicitly sealed, a class isn't. A struct can't be abstract, a class can. A struct can't call : base in its constructor whereas a class with no explicit base class can. A struct can't extend another class, a class can. A struct can't declare protected members for example, fields, nested types a class can. A struct can't declare abstract function members, an abstract class can.

A struct can't declare virtual function members, a class can. A struct can't declare sealed function members, a class can. A struct can't declare override function members, a class can. The one exception to this rule is that a struct can override the virtual methods of System. As previously mentioned: Classes are reference type while Structs are value types with all the consequences. Besides the basic difference of access specifier, and few mentioned above I would like to add some of the major differences including few of the mentioned above with a code sample with output, which will give a more clear idea of the reference and value.

There is one interesting case of "class vs struct" puzzle - situation when you need to return several results from the method: choose which to use. If you know the ValueTuple story - you know that ValueTuple struct was added because it should be more effective then Tuple class.

But what does it mean in numbers? This is true, however also note that as of. NET 2 structs support a Nullable version and C supplies some syntactic sugar to make it easier to use. Every variable or field of a primitive value type or structure type holds a unique instance of that type, including all its fields public and private. By contrast, variables or fields of reference types may hold null, or may refer to an object, stored elsewhere, to which any number of other references may also exist.

The fields of a struct will be stored in the same place as the variable or field of that structure type, which may be either on the stack or may be part of another heap object. Creating a variable or field of a primitive value type will create it with a default value; creating a variable or field of a structure type will create a new instance, creating all fields therein in the default manner. Creating a new instance of a reference type will start by creating all fields therein in the default manner, and then running optional additional code depending upon the type.

Copying one variable or field of a primitive type to another will copy the value. Copying one variable or field of structure type to another will copy all the fields public and private of the former instance to the latter instance. Copying one variable or field of reference type to another will cause the latter to refer to the same instance as the former if any. If a type implements mutable value semantics, copying one variable of that type to another copies the properties of the first to another instance, referred to by the second, and using a member of the second to mutate it will cause that second instance to be changed, but not the first.

If a type implements mutable reference semantics, copying one variable to another and using a member of the second to mutate the object will affect the object referred to by the first variable; types with immutable semantics do not allow mutation, so it doesn't matter semantically whether copying creates a new instance or creates another reference to the first. NET, it is possible for value types to implement any of the above semantics, provided that all of their fields can do likewise.

A reference type, however, can only implement mutable reference semantics or immutable semantics; value types with fields of mutable reference types are limited to either implementing mutable reference semantics or weird hybrid semantics. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. What's the difference between struct and class in.

Ask Question. Asked 13 years, 3 months ago. Active 11 days ago. Viewed k times. Improve this question. Mark Amery k 62 62 gold badges silver badges bronze badges.

Keith Keith k 69 69 gold badges silver badges bronze badges. Good quesstion, it helped me as well. Each object is associated with the data of type class with which it is created. Thus we can also say that class is a collection of objects of similar types. It is a user defined data type and behaves like built-in data type of the language. Since class has data and methods to manipulate the data, it supports one of the most important features of OO: Data Encapsulation.

Structure declaration forms a template which can be used to create structure objects. The variables inside a structure are called members. Generally all the members of a structure are logically related.