Reading assignment - auto variables

[Rudd]

What is an auto variable?
Auto variable is when a placeholder type appears as an expr. It is when auto X equal expr. The type is derived from the initialiser when the placeholder type is constraint.

Why is it convenient to use?
It simplifies when the placeholder type specifier is auto or type-constraint auto (since C++20), the variable type is deduced from the initializer using the rules for template argument deduction from a function call.

When should you use it?
Enable it possible to use template operators to use, since there is no syntax to specify template arguments for an operator other than by re-writing it as a function call expression:

When will the type of an auto variable be determined (compile-time or run-time?)
Template argument deduction attempts to determine template arguments, which can be substituted into each parameter P to produce the type deduced A, which is the same as the type of the argument A, after adjustments listed below. If there are multiple parameters, each P/A pair is deduced separately and the deduced template arguments are then combined.

[Uyan]

1. An auto variable is a variable whose type will be decuded automatically by the computer based on its initialization. For example:

auto a = 3;
auto b = 3.14;

The computer will deduce that a is an int, while b is a double.

2. It is convenient to use auto variables to save time typing and for flexibility when multiple input variables are being used.

3. You should use auto variable when you know your initial values but don’t and/or won’t know your outputs’ type.

4. An auto variable’s type will be determined during compile-time, which is before run-time.

[Dougal]

• What is an auto variable?
  An auto variable is a variable whose data type is detected automatically from the expression

• Why is it convenient to use?
  It’s convenient because it 1) data type might not be initially known, 2)reduces mundane work of repeatedly entering the data type 3) improves code readability

• When should you use it?
  Auto variables should be used when it is unknown or can’t be immediately known what data types will be used or the result thereof.

• When will the type of an auto variable be determined (compile-time or run-time?)
  When the program is compiled

[vinicanhaci]

1. What is an auto variable?
   Auto will find the type of the variable being declared on its own.

2. Why is it convenient to use?
   Allows more flexibility to code

3. When should you use it?
   When you are unsure of the type of the variable that will be used.

4. When will the type of an auto variable be determined (compile-time or run-time?)
   Compile-time

[John_Nutter]

1. What is an auto variable? A variable which its type automatically deduced by its initializer
2. Why is it convenient to use? When you don’t know data type of a variable or return type of a function, and save time.
3. When should you use it? when reusing lambda expressions and replacing long data types, to improve readability.
4. When will the type of an auto variable be determined (compile-time or run-time?)Auto variables is deduced at compile-time.

[ol_frank]

1. What is an auto variable?
   An auto variable is a variable that its type is automatically drawn by its initialiser

2. Why is it convenient to use?
   If you do not know the data type of the variable you are initialising. Also a function return type is not always known thus would be beneficial to use an auto variable.

3. When should you use it?
   When reusing anonymous functions or replacing long data types. It also makes you code more readable

4. When will the type of an auto variable be determined (compile-time or run-time?)
   Compile time

[Samuel1]

1. Auto variable is automatically detected variable.
2. It makes working with functions easier. Can be used when it is the sole constituent of the declared type.
3. You would use it with a corresponding for loop.
4. Compile time

[walter_w]

1. A type that is inferred by the type of the variable on the right hand side
2. no need to know the variable type
3. as a programming convenience whenever the type can be inferred
4. compile time

[Asit]

@filip

• What is an auto variable?
• Why is it convenient to use?
• When should you use it?
• When will the type of an auto variable be determined (compile-time or run-time?)

What is an auto variable?

The auto type is a specifier that automatically deduces the type of the variable from it’s the initializer.

Why is it convenient to use?

An auto variable is convenient to use because it will automatically assign the type. This allows the user not to spend brainpower on knowing or guessing the type especially since C++ is very strict with it’s compiler.

When should you use it?

This is used when the type of variable that might be passed in is unknown, or when the type is unusually complex.

When will the type of an auto variable be determined (compile-time or run-time?)

The type of the auto variable will be determined at compile-time.

[juanjs]

1. Auto variable is a placeholder type specifier. The placeholder type specifier is auto or the variable is deduced from the initializer in compilation.

2. The auto variable can simplify long data type placeholders specifiers. It makes declaring variables simpler and it produces cleaner code for the developer.

3. I should use the auto variable for replacing lengthy data types. And to storing lambda expressions to improve readability and reduce code complexity.

4. The auto variable type is determined during compilation.

[Eric_Toronto]

1. What is an auto variable?
   An auto variable is a variable whose type is automatically deduced by the value assigned to it or the result of its initializer.

2. Why is it convenient to use?
   It is convenient because programmers do not have to worry about type matching when declaring variables, thus saving time and energy by not necessarily writing out types explicitly and making sure the declaration and assignment are agreed on the same type.

3. When should you use it?
   Auto variables may be used when the data type is a long and complex expression or when maintaining typing becomes tedious.

4. When will the type of an auto variable be determined (compile-time or run-time?)
   The type of an auto variable will be determined at compile-time.

[Jason_Mack]

1. What is an auto variable?

A placeholder that is replaced by a class or enumeration type following the rules for placeholder deduction.

2. Why is it convenient to use?

auto&& may be deduced either as an lvalue reference or rvalue reference according to the initializer, which is used in range-based for loop.

3. When should you use it?

in the type specifier of a variable, If the placeholder type specifier is used to declare multiple variables, in the type-id of a new expression.
4. When will the type of an auto variable be determined (compile-time or run-time?)
run time.

[WhitneyPaterson]

1. What is an auto variable?
   The auto keyword specifies that the type of the variable that is being declared will be automatically deducted from its initializer.

2. Why is it convenient to use?
   Helps increase readability, saves time, and flexible.

3. When should you use it?
   When the type of variable being passed is not yet known.

4. When will the type of an auto variable be determined (compile-time or run-time?)
   Compile-time.

[ycasanova]

1. What is an auto variable?
   Auto variables is in C++ and they are used to automatically assigns a variaty of types to the variable name

2. Why is it convenient to use?
    **Its convenient because it helps clarify the code by allowing the C++ compiler find out the type of the variables.**

3. When should you use it?
   People can use it anywhere, the C++ compiler can take away the targeted type and avoid it whenever there might be a mistake that happened.

4. When will the type of an auto variable be determined (compile-time or run-time?)
   **The compiler will check and make sure to find the necessary type of variable/variables.**

[Jason_Purcell]

1. What is an auto variable?
   a variable that has its type auto deduced by its initializer.

2. Why is it convenient to use?
   makes lenghty data type specifiers easier by using the auto keyword instead of writing out the whole type specifier expression.

3. When should you use it?
   its used to store reused lambda expressions and long data types to improve readability and complexity.

4. When will the type of an auto variable be determined (compile-time or run-time?)
   run time.

[Konzaih]

1.) A Variable whose type will be automatically deduced from the initializer
2.) Simpler Code
3.) If you aren’t sure of the type. If its used instead of a longer expression it might increase compilation time.
4.) At compile time as every declaration needs a type at compilation time

[Gry]

1. What is an auto variable?

Variable automatically deduced from the initializer

2. Why is it convenient to use?
   Saves time and makes code more readable

3. When should you use it?
   When maintaining typing becomes too tedious.

4. When will the type of an auto variable be determined (compile-time or run-time?)
   Compile time

[jak]

What is an auto variable?

An auto variable is a variable which is declared with a complicated type. This can include initializing it to a template, or a pointer to a function etc.

Why is it convenient to use?

auto variables can be convenient to use when we don’t know what data it will include yet.
For example, we may declare an auto variable and assign a function to it, but we don’t know what the return value will be.

When should you use it?

auto variables should be used in a situation where it could improve readability of your code.
They should also be used to store repeatable expressions.

When will the type of an auto variable be determined (compile-time or run-time?)

The type of an auto variable will be determined at compile-time.

[serba]

1 - What is an auto variable?

An auto variable is a placeholder type specifier whose type will be automatically deduced from the initializer.

2 - Why is it convenient to use?

Gives flexibility to functions when the type is unknown or when using multiple variable types.

3 - When should you use it?

When you don’t know what variable types will be passed in.

4 - When will the type of an auto variable be determined (compile-time or run-time)?

The type of an auto variable will be determined at compile time as the compiler automatically detects the variable’s data type.

[Alexlane8]

1. What is an auto variable?

an automatic variable is a local variable which is allocated and deallocated automatically when program flow enters and leaves the variable’s scope. The scope is the lexical context, particularly the function or block in which a variable is defined.

2. Why is it convenient to use?

Allows a programmer to leave the type deduction to the compiler itself.
With type inference capabilities, we can spend less time having to write out things the compiler already knows.

3. When should you use it?

Good use of auto is to avoid long initializations when creating iterators for containers. The variable declared with auto keyword should be initialized at the time of its declaration only or else there will be a compile-time error.
The auto keyword has many uses, including but not limited to variables, functions, pointers, iterators, templates, and many more.

4. When will the type of an auto variable be determined (compile-time or run-time?)

Compile-time. Types cannot be determined at runtime. The type of every expression must be known at compile time.