Variables in C++ - Reading Assignment

[piciu]

1. a named object
   2.A named object is called a variable, and the name of the object is called an identifier
   3.It means that the object was created and assigned a storage in the memory

2. A declared variable before defining it

3. A random behavior of an code that has not been well defined

[Erich_Assuncao]

1. It is a named object that typically refers to data structure in memory. In simple terms, a named region in memory.

2. It is the name given to a variable.

3. It refers to the creation and assignment of an object to a memory address.

4. l-values have a memory address, r-values don’t.

5. A variable that has not been instantiated. The behaviour will be unpredictable.

6. Undefined behavior is the result of executing code whose behavior is not well defined by the C++ language. In this case, the C++ language doesn’t have any rules determining what happens if you use the value of a variable that has not been given a known value.

[jgentry]

1. A variable in C++ is an object.

2. The definition of a variable is a named object.

3. Instantiation of a variable is the process by which the object is created and assigned a memory address.

4. An I-value has been instantiated while an r-value has not been instantiated (could not find a word-for-word answer in the article).

5. An uninitialized variable is a variable that is undefined. You can thus expect undefined behavior in your code.

6. Undefined behavior occurs when you define multiple variables in C++ incorrectly.

This is the best I could do. Those last two questions were a challenge. Thank you!

[Alko89]

Good job! undefined behavior can also be other things, basically everything that is not well defined in the language

[write2tapas]

1. A variable is an object which stores values.
2. A portion of memory to store a value.
3. Declaration of a variable with its type is called instantiation of a variable.
4. I-value is the name or identifier of a variable and r-value is the value it holds in memory.
5. An uninitialized variable means its value is not declared before the program runs. If the initial value of a variable is not declared , a program may provide unpredictable results while it runs , or it may give error.
6. Undefined behavior means program generates results in unpredictable manner.

[Thomas_VL]

1. What is a variable in C++?
An object with a name used to store values

2. What is Definition of a variable?
A piece of memory that has a name and is currently defined and may be defined and vary based on another piece of memory.

3. What is Instantiation of a variable?
Defining and initializing a value in the same step.

4. What is the difference between an l-value and an r-value?
An l-value is persistently defined in memory. An r-value is not defined persistently and may be considered the variation of the l-value variable.

5. What is an uninitialized variable and what kind of behavior can you expect from such a variable?
A variable that has no memory location. We can expect anything except what we expected the variable value to be.

6. What is undefined behaviour?
The resulting value of an uninitialized variable.

[guillepc2015]

1. An object with a name.
2. A variable is a storage location (identified by a memory address) paired with an associated symbolic name, which contains some known or unknown quantity of information referred to as a value.
3. At compile time, when the compiler sees this statement, it makes a note to itself that we are defining a variable, giving it its name and its type.
4. An l-value is defined in memory. An r-value is not defined in memory.
5. A variable with no memory location and the program may provide unpredictable results while it runs or it may give error.
6. Undefined behavior is the result of executing code whose behavior is not well defined by the C++ language. In this case, the C++ language doesn’t have any rules determining what happens if you use the value of a variable that has not been given a known value.

[GalacticBrainBomb9]

1. Most of the objects that we create in computer programs will be variables. In general programming, the term object typically refers to a variable, data structure in memory, or function. A named object is called a variable.

2. a special kind of declaration statement. When the compiler sees this statement, it makes note to itself that we are defining a variable.

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

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

5. An uninitialized variable is basically a programming error. It is not set to a definite known value before it is used. one can expect unpredictable behavior from such a variable.

6. Undefined behavior is returned from trying to execute code that is not recognized by the language.

[Thijs.Smit]

1. What is a variable in C++?
   A variable is a named region of memory.

2. What is the Definition of a variable?
   A variable is an object with an identifier, type and value. It is used to acces memory

3. What is Instantiation of a variable?
   making an instance of the variable

4. What is the difference between an l-value and an r-value?
   an l-value is something that points to a specific memory location.
   a r-value is something that doesn’t point anywhere.

5. What is an uninitialized variable and what kind of behavior can you expect from such a variable?
   a variable that has never been initialized or assigned a value

6. What is undefined behavior?
   When for instance a uninitialized variable gets used and it can contain anything. therefore the end result is undefined.

[Atlas]

What is a variable in C++?

Variable is an object which is named.

What is Definition of a variable?

Object type and a string value as variable, if it is necessary there also assigned value with a equal sign.
int x = 1;

What is Instantiation of a variable?

Assignation of variable to the computer’s memory address.

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

Rvalue refers to a memory location, lvalues refer to a data value.

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

Uninitialized means the object has not been given a known value. i.e. int x; value may gets returned as a coincidence from the memory which were holding unpredictable integer value from one forgotten job.

What is undefined behaviour?

Using the value from an uninitialized variable is our first example of undefined behavior. Undefined behavior is the result of executing code whose behavior is not well defined by the C++ language.

[Rob_McCourt]

1. A variable in C++ is a named Object. Objects are how we command the computer to access a piece of Data located in our Computer

2. You need a definition to create a Variable for example int x

3. When an object is instantiated it is created and assigned a memory address. This has to happen before they can store variables.

4. L-Value, can be understood like the locator value, it is the address in memory for an object
   R-Value is the actual value such as a character or a number which is stored in an address in memory

5. Its is a variable that has not been given a known value. If used it will create whatever value is present at its memory location which can be different each time it is accessed. This will cause random unpredictable results.

6. No rules on C++. Undefined behaviour happens at a result of uninitialised variables. This can catch you out later down the line when programming on C++

[mburtonshaw]

A variable stores data under a name (or identifier) at a location.

The Definition of a variable is the naming of a variable.

The instantiation of a variable is when it is assigned a memory class.

An l-value is the location where a variable is stored on the RAM. An r-value is the actual “value” or data stored in the variable.

An uninitialized variable is assigned to a space in memory, but it doesn’t have a value. This can cause unexpected results, or undefined behavior.

Undefined behavior is any behavior that is unexpected from a written program.

[Timmy]

A variable is an object that has a name to store values.

Each variable has a specific type, which determines the size and layout of the variable’s memory.

Instantiation is when a new instance of the class is created (an object).
When an class is instantiated memory is allocated for the object and the classes constructor is run.

l-value is anything whose address is accessible. It means we can take address of lvalue using & operator.
r-value is anything that is not l-value. It means we cannot take address of r-value and it also don’t persist beyond the single expression.

An uninitialized variable is a variable that is declared but with no value assigned to it.
It can behave unpredictable and chance of error.

Undefined behavior is the result of executing code whose behavior is not well defined by the language. The program may fail to compile, or it may execute incorrectly.

[MBF-Lifestyle]

1: A variable is a named object in C++

2:Definition of a Variable is both the type and name for the variable

3:What is Instantiation of a variable: It is the random access memory.

4: What is the difference between an I-value and an r-value.
The I-value has a persistent address while an I-value does not have a persistent address.

5: What is an uninitialized variable and what kind of behaviour can you expect from such a variable.
An uninitialized variable is in the memory of the program ; but does not have an assigned value to it , so unpredictable stuff can happen.

6: What is undefined behaviour?
When a program can work well for a few runs ,then not execute after a while due to undefined behaviour error.

[Rob_McCourt]

Hi all, Can i ask a question regarding Syntax on C++. Ivan doesnt explain what “<<” LESS THAN signs do? What is the purpose of them.

Thanks.

[Alko89]

<< are so called insertion operators, they are used to send a stream of data to an output.

For example using cout << "Hello world" will send the string of data to a standard output, by default this is the console screen, which means it will print “Hello world” to your console output.

[ThreeHeadsUp]

1. a variable is a named object in the code
2. a statement in the code meant to define a variable- that means to specify its type and give it a name
3. when a variable is instantiated it is ‘brought into existence’ inside the code, a memory address is assigned to it, but the memory slot itself is (usually) empty in the start
4. l-values reside in the memory, r-values are discarded at the end of a statement
5. uninitialized variables have no set starting value, defined in the code itself. we can expect random behavior, as the values can be a seeming random string, leftovers from previous memory usages, nulls, whatever.
6. undefined behavior is the result we get when code with poorly defined variables is executed

[JeremyH]

1. What is a variable in C++?
   – A variable in C++ is a named object that is used to store a value.

2. What is Definition of a variable?
   – A variable is a special kind of declaration statement that is used to create a variable.
   – For example: int x;

3. What is Instantiation of a variable?
   – Instantiation of a variable occurs during run-time and is the actual creating of an instance of a variable that has been defined and assigning it a memory address

4. What is the difference between an l-value and an r-value?
   – The l-value is the memory area, or named object, or variable that usually appears on the left side of an assignment or initialization. Whereas the r-value is the value or expression that can only appear on the right side of the assignment or initialization.

5. What is an uninitialized variable and what kind of behavior can you expect from such a variable?
   – An uninitialized variable is a variable that has not been given a known value (either through initialization or assignment) and the behavior might not be what you expect because the variable could contain any arbitrary (or garbage) value that was at the memory address given to the variable when the the variable was defined.

6. What is undefined behavior?
   – Undefined behavior is what happens when you run code for which the behavior has not been accounted for by the C++ language. Undefined behavior is the result of executing code whose behavior is not well defined by the C++ language.

[MarkM]

1. What is a variable in C++?

A value stored by an object

2. What is Definition of a variable?

the term object typically refers to a variable, data structure in memory, or function. In C++, the term object has a narrower definition that excludes functions.

3. What is Instantiation of a variable?

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

An l-value is a variable that has a persistent address in memory.

An r-value is usually temporary and is discarded at the end of the statement in which they occur.

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

A variable that has not been given a known value. You can expect unpredictable behavior.

6. What is undefined behaviour?

The result of executing code whose behavior is not well defined by the programming language.

[Hirbed]

Reading Assignment: Variables in C++

1. What is a variable in C++?

A variable is a named object or identifier in memory, it’s only a memory location to store some value at .

2.What is Definition of a variable?

When you decide what type of data to store in a specific variable, as string or integer.

3. What is Instantiation of a variable?

When the program is executed the compiler will automatically assign a memory address and create a object pointing to uniquely created address space in memory.

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

lvalue is anything whose address is accessible. It means we can take address of lvalue using & operator. Rvalue is anything that is not lvalue. It means we cannot take address of rvalue and it also don’t persist beyond the single expression.

5. What is an uninitialized variable and what kind of behaviour

can you expect from such a variable?

It’s only a variable space, without any value assigned that can return a random value.

6. What is undefined behaviour?

A return a random value, as when using a uninitialized variable, will create bugs in your program as it’s will be different values returned from a function time to time