Variables in C++ - Reading Assignment

[Vote3rdParty]

1. A variable in C++ is a named object, “An object is a region of storage (usually memory) that has a value and other associated properties…” - https://www.learncpp.com/cpp-tutorial/introduction-to-variables/
2. When defining a variable, we give it a name or corresponding value by using a declaration statement.
3. Instantiation of a variable is an instance of a variable being used or being run; “the object will be created and assigned a memory address.” - https://www.learncpp.com/cpp-tutorial/introduction-to-variables/
4. I-values are associated with a memory address, r-values are not.
5. An unintialized variable is a variable that is not currently in use, we can expect it to stay dormant until used.
6. Undefined behavior means there are no restrictions on the behavior of the program.

[serba]

@ivan

• What is a variable in C++?
• What is the Definition of a variable?
• What is Instantiation of a variable?
• What is the difference between an l-value and an r-value?
• What is an uninitialized variable and what kind of behavior can you expect from such a variable?
• What is undefined behavior?

• In C++, a named object is called a variable, and we use variables to access memory.

• Definition of a variable is a declaration statement used to create a variable.

• Instantiation of a variable means an object will be created and assigned a memory address.

• An l-value is a named variable that has an address in memory, a locator value. It points to a specific memory location. It goes on the left side of an assignment.
  An r-value does not point to any memory location. It goes on the right hand side of an assignment.

• An uninitialized variable is a variable that has not been given a known value or assignment. This kind of variable can result in undefined behavior.

• Undefined behavior when a program is compiled and the result is unexpected.

[gwen]

An object with a name.
Specifying a type and a name for a variable for example
Allocation of memory in RAM for a variable

An l-value has a persistent address. An r-value hasn’t a persistent address.

An uninitialized variable is in memory, but she doesn’t have value assigned to it. Using such a variable can cause unexpected behavior.

Undefined behavior is when the result of the program may exhibit unexpected results. He can work well the three first executions and not at the fourth for example.

[CaliCrypto22]

Q: What is a variable in C++?
A: A variable in C++ is a named object.

Q: What is the Definition of a variable?
A: A region of storage (memory location) that has a value and other associated properties.

Q: What is Instantiation of a variable?
A: Instantiation means the variable will be created and assigned a memory address.

Q: What is an uninitialized variable and what kind of behavior can you expect from such a variable?
A: An uninitialized variable is not assigned a value. The compiler may or may not complain. If it doesn’t, your program may intermittently crash and produce sporadic results.

[Ishoboy]

1. A named object.

2. It is a special kind of declaration statement.

3. Is a fancy word that means the object will be created and assigned a memory address.

4. l-value refers to memory location which identifies an object. Whilst r-value refers to
   data value that is stored at some address in memory.

5. An uninitialized variable is a variable with no given value. The kind of behavior that can be expected from such variable is called undefined behavior.

6. Undefined behavior is the result of executing code whose behavior is not well defined by the C++ language.

[PapatoniC]

1. What is a variable in C++?
   An space on the memory that store a value that can change during application lifecycle
2. What is Definition of a variable?
   It is how we create a variable
3. What is Instantiation of a variable?
   It ocurrs when a variable is allocated in a memory space to store a value
4. What is the difference between an l-value and an r-value?
   l-value remains since created during all app lifecycle , while rvalue only persist on the expression where it is executed
5. What is an uninitialized variable and what kind of behaviour can you expect from such a variable?
   A variable without any defined value , so it could lead to undefined behaviours because its value can be anything or null.
6. What is undefined behaviour?
   A behabiour that the application is not able to manage , so it can cause even an application crash

[SabineB]

1. What is a variable in C++?

Variable is a named objective in C++. It’s name is called identifier.

2. What is the Definition of a variable?

Definitions is a declaration statement that consists of variable type and variable name.

3. What is Instantiation of a variable?

Instantiation is a process that means the object will be created and assigned a memory address. Variables must be instantiated before they can be used to store values.

4. What is the difference between an l-value and an r-value?

L-value is an expression that refers to an object. Historically the definition of l-value was “an object that can appear on the left-hand side of an assignment”, but this is not accurate anymore as const is l-value, but cannot appear on the left-side. R-value is an expression that can appear only on the right-hand side of an expression.

5. What is an uninitialized variable and what kind of behaviour can you expect from such a variable?

Uninitialized variable is a variable that has not been given a known value. It does not initialize a given value automatically (for example zero). It can lead to undefined behaviour as we cannot predict what will happen. It can be easily initialized, if the programmer decides to assign value to it.

6. What is undefined behaviour?

Undefined behavior is the result of executing code whose behavior is not well defined by the C++ language.

[kryptoslav]

1. named object
2. data structure in memory
3. creation and memory space assignment to variable
4. I-value has persistent address, R-value does not
5. such a variable is in memory but does not have assigned value, unexpected behaviour can cause usage of such a value
6. result of code whose behaviour is not properly defined

[shaakirah_B]

1. What is a variable in C++?
   a named object

2. What is the Definition of a variable?
   a special kind of declaration for a variable

3. What is the Instantiation of a variable?
   the piece of memory set aside within the RAM

4. What is the difference between an l-value and an r-value?
   I-value has a memory address and a r-value doesn’t have a dedicated memory address

5. What is an uninitialized variable and what kind of behavior can you expect from such a
   variable?
   a variable that has not been given a value

6. What is undefined behavior?
   the result of executing a program whose behavior is prescribed to be unpredictable

[porter]

1. A variable in C++ is a named region where the memory is stored.
2. A variable is the name of an object where value or other properties are stored.
3. Instantiation of a variable is the creation of the object and it being assigned a memory address.
4. l-value expressions only appear on the left side and r-value expressions can only appear on the right side.
5. A variable that is declared but does not have a definite value. Usually causes bugs.
6. A program being executed and the it results in behavior that is unpredictable and sounds like demons may be created too

[waka]

1. An object is a region of storage that has value and other assigned properties. When such an object is named, it is called a variable.
2. To create a variable a declaration statement is used which is called a definition.
3. When a program is run, a variable is instantiated. This means that the object is created and assigned to a memory address.
4. In C++ an lvalue is something that points to a specific memory location. On the other hand, a rvalue is something that doesn’t point anywhere.
5. An uninitialized variable is an object that hasn’t been created yet and isn’t assigned an address yet.
6. For undefined behaviour, there are no restrictions on the behavior of the program. This will result in compilers producing unexpected behaviour.

[muradawad]

1. What is a variable in C++?
   A variable is a name given to a memory location. It is the basic unit of storage in a program. The value stored in a variable can be changed during program execution. A variable is only a name given to a memory location, all the operations done on the variable effects that memory location.

2. What is the Definition of a variable?
   In computer programming, a variable or scalar is a storage location paired with an associated symbolic name, which contains some known or unknown quantity of information referred to as a value.

3. What is Instantiation of a variable?
   Initializing a variable means specifying an initial value to assign to it (i.e., before it is used at all). Notice that a variable that is not initialized does not have a defined value, hence it cannot be used until it is assigned such a value.

4. What is the difference between an l-value and an r-value?
   an lvalue is an object reference and an rvalue is a value. The difference between lvalues and rvalues plays a role in the writing and understanding of expressions. … An lvalue always has a defined region of storage, so you can take its address. An rvalue is an expression that is not an lvalue.

5. What is an uninitialized variable and what kind of behavior can you expect from such a variable?
   In computing, an uninitialized variable is a variable that is declared but is not set to a definite known value before it is used. It will have some value, but not a predictable one. As such, it is a programming error and a common source of bugs in software.

6. What is undefined behavior?
   in computer programming, undefined behavior (UB) is the result of executing a program whose behavior is prescribed to be unpredictable, in the language specification to which the computer code adheres.

[zai]

@ivan

Welcome to the discussion about the reading assignment about Variables in C++.

Leave your answers to the questions below in this thread. If you have any questions or you want to discuss something connected to the assignment feel free to do it in this thread as well, but please keep everything to the topic.

1. What is a variable in C++?
2. What is the Definition of a variable?
3. What is Instantiation of a variable?
4. What is the difference between an l-value and an r-value?
5. What is an uninitialized variable and what kind of behavior can you expect from such a variable?
6. What is undefined behavior?

1. In C++, a variable is an object that is named.

2. In order to create a variable, we use a special kind of declaration statement called a definition.

3. Instantiation is a fancy word that means the object will be created and assigned a memory address. Variables must be instantiated before they can be used to store values.

4. An l-value is a variable that has a memory address while an r-value is a variable without an address since these are values that are discarded at the end of a statement.

5. A variable that has not been given a known value (usually through initialization or assignment) is called an uninitialized variable which leads to unpredictable results or behavior.

6. Undefined behavior is the result of executing code whose behavior is not well defined by the C++ language.

[Louiseee618]

1. What is a variable in C++?

Variable is the term used for a named object. It is a region of storage that has a value and other associated properties.

2. What is the Definition of a variable?

It is a name given to a memory location.

3. What is Instantiation of a variable?

It is a fancy word that means the object will be created and assigned a memory address.

4. What is the difference between an l-value and an r-value?

The l- value stores the address of the unit and the r - value stores the actual value of the unit.

5. What is an uninitialized variable and what kind of behavior can you expect from such a variable?

Uninitialized variable is a variable that has not been given a known value (usually through initialization or assignment).
The computer will assign some unused memory to the uninitialized variable.

6. What is undefined behavior?

Undefined behavior happens when a computer language does not handle a certain operation that is coded into a codebase.

[Javier_Flores]

Reading Assignment: Variables in C++ (Answers)

1. A named object is a variable.
2. A declaration statement.
3. Where an object is created and assigned a memory address.
4. Each is its separate object variable.
5. A variable that is not assigned a value, it would execute different behavior every time.
6. The result of executing code whos behavior is not defined by C++ language, so result show different side effects.

[HGarach]

1. What is a variable in C++?
   Ans: An object is a region of storage (usually memory) that has a value and other associated properties and a named object is called a variable

2. What is the Definition of a variable?
   Ans: In order to create a variable, we use a special kind of declaration statement called a definition. Here’s an example of defining a variable named x:
   int x; // define a variable named x, of type int

3. What is Instantiation of a variable?
   Ans: Instantiation is a fancy word that means the object will be created and assigned a memory address. Variables must be instantiated before they can be used to store values. For the sake of example, let’s say that variable x is instantiated at memory location 140. Whenever the program then uses variable x, it will access the value in memory location 140.

4. What is the difference between an l-value and an r-value?
   Ans: l-value has a persistent address but r-value is not associated with a persistent memory address

5. What is an uninitialized variable and what kind of behavior can you expect from such a variable?
   Ans: It is a variable that has not been assigned a memory address. The behavior that one can expect to see is that the compiler will assign a random space in the memory which can change every time you run and compile the code.

6. What is undefined behavior?
   Ans: It is behavior is not well defined by the programming language.

[RhoadsNRoses82]

1. A variable is one type of “object” that C++ uses to reference the computer’s memory. It stores the value of the variable in a specific portion of the memory, to be accessed later, avoiding the need to directly reference the memory blocks with code.
2. Defining a variable is simply telling the computer that the variable exists, and what type of variable it is. It doesn’t yet have to have any value associated with it.
3. instantiation of the variable is when that variable gets assigned to a specific section of the memory
4. i values have permanent memory address, while r values usually are temporary.
5. An uninitialized variable is a variable that has not been assigned a value.
6. This typically results in the variable being assigned whatever data is already present in the particular memory location to which the variable got linked. This value may change each time the program is run.

[RCV]

1. A named object.
2. Definition of a variable is a declaration statement.
3. Instantiation of a variable means the object will be created and assigned a memory address.
4. l-values are usually standing on a left side of an expression, and the are representing memory containers that can point to some data. R-values stand on the right side, and they get determined as values and get assigned to l-values on the left
5. It is a variable, that doesn’t have anything assigned in this particular program, but sometimes a random value in memory is being assigned to it without us knowing it. Unexpected behaviour from this variable
6. It is a behaviour, that can be changing every time I run the code - it is not consistent at all

[Basilios]

1. What is a variable in C++?
A named object
2. What is the Definition of a variable?
A variable is a name given to a memory location
3. What is Instantiation of a variable?
allocation and reserving Ram for a function
4. What is the difference between an l-value and an r-value?
an l-value has a fixed address where a r-value doesn’t
**5. What is an uninitialized variable and what kind of behaviour can you expect from such a variable?**An uninitialized variable is in memory, but it doesn’t have value assigned to it. Using such a variable can cause unexpected behaviour.
6. What is undefined behavior?
Unpredictable behaviour resulting from the use of uninitialized variables, because C++ has no rules determining what happens.

[cincinnato]

1. What is a variable in C++? Is a named object stored in the RAM
2. What is Definition of a variable? It’s a special kind of declaration statement that is used to create a variable
3. What is Instantiation of a variable? It is referred to the assignment of a memory address to a variable.
4. What is the difference between an l-value and an r-value? A left-value has a persistent location on the RAM and can be recalled every time is needed; a right-value is basically a temporary value that is not located on memory and is discarded after its use.
5. What is an uninitialized variable and what kind of behaviour can you expect from such a variable? It is a declared variable but not instantiated. Since the memory block has not been determined the object may get any information already present on memory block with unpredictable results.
6. What is undefined behaviour? Is the result of a not well defined coding. That might be unpredictable.