Chapter 6

Question 1

Compound Statement

Answer 1

Also called block, is a group of zero or more statements that is treated by the compiler as a single statement

Question 2

Block structure

Answer 2

Begins and ends with curly braces {}
Statement to be executed in between braces
No semicolon is needed

Question 3

Nesting blocks

Answer 3

Enclosing block is called outer block, the enclosed block is called inner or nested block

Question 4

Use of blocks

Answer 4

In conjunction with if statements, if we want multiple statements to execute when the condition evaluates to true

Question 5

Nesting level (depth)

Answer 5

The maximum number of blocks you can have in a function, inuding outer block

Question 6

Defining a namespace

Answer 6

Via namespace keyword

Question 7

User defined namespaces

Answer 7

Namespaces you create for your own declarations

Question 8

Scope resolution operator (::)

Answer 8

Used to look for an identifier in a particular namespace, identifier specified by the right operand should be looked for in the scope of the left operand

Question 9

Scope resolution with no prefex

Answer 9

The identifier is looked for in the global namespace

Question 10

Multiple namespace blocks

Answer 10

You can declare namespace blocks in multiple locations, all declarations within the namespace are considered part of the namespace

Question 11

Nested namespaces

Answer 11

We can acces as ex. foo::goo::add

Question 12

Namespace aliases

Answer 12

Allow us to temporarily shorten a long sequience of namespaces into something shorter

Question 13

Use of namespaces

Answer 13

• in applications, to seperate application-specific code from code that can be reused
• when you want to distribute the code
• to allow the user to see the contents of your library

Question 14

Identifier’s Scope

Answer 14

Determines where an identifier can be accessed within the source code, compile time property

Question 15

Block scope

Answer 15

Variables are in in scope from their point of definition to the end of the block the variables are defined within

Question 16

Variables names

Answer 16

Must be unique within a given scope

Question 17

Variables storage duration

Answer 17

Determines what rules govern when and how a variable will be created and destroyed

Question 18

Automatic storage duration

Answer 18

In local variables, which means they are created at the point of definition and destroyed at the end of the block they are defined in

Question 19

Local variables in nested blocks

Answer 19

Limited to the inner block, not accessible in the outer block, variables defined in outer block can be accessed in the inner blocks

Question 20

Linkage

Answer 20

Property of identifiers, it determines whether other declarations of that name refers to the same object or not, local variables don’t have linkage

Question 21

Defining variables

Answer 21

Should be defined in the most limited scope

Question 22

Global variables

Answer 22

Variables declared outside of a function

Question 23

Declaring global variables

Answer 23

At the top of a file, below the includes, above any code

Question 24

Naming global variables

Answer 24

Using a g or g_ prefix

Question 25

File scope (global scope)

Answer 25

They are visible from the point of declaration till the end of the file in which are declared

Question 26

Static duration

Answer 26

Variables created when the program starts and it is destroyed when it ends

Question 27

Initialization of global variables

Answer 27

Default zero-initialized, can be initialized optioanally, can be constants but they must be initialized

Question 28

Name hiding/ shadowing

Answer 28

When we have a variable inside a nested block that has the same name as a variable in an outer block, nested one hides the outer when they both are in scope

Question 29

Shadowing global variables

Answer 29

Local variables will shadow the global variable wherever the local variable is in scope

Question 30

Using global instead of local variable

Answer 30

With using the scope operator (::), with no prefix

Question 31

Avoiding shadowing

Answer 31

Shadowing of global variables can be avoided by using a g_ prefix on all global names

Question 32

Internal linkage identifier

Answer 32

Can be seen and used within a single file, but not from other files, if two files have identifiers with the same name will be treated as independent

Question 33

Internal variables

Answer 33

Global variables with internal linkage

Question 34

Making non-constant variables internal

Answer 34

By using static keyword

Question 35

Storage class specifier

Answer 35

Sets both the names linkage abd its storage duration

Question 36

Common storage class specifiers

Answer 36

Static, extern and mutable

Question 37

Independent entities

Answer 37

Internal objects and functions that are defined in different files

Question 38

Linkage property

Answer 38

Of identifier, function identifiers have the same linkage property as variable identifiers

Question 39

Functions linkage

Answer 39

Default is external linkage, but it can be set to internal via the static keyword

Question 40

Identifier with external linkage

Answer 40

Can be seen and used bpth from the file in which ate defined and from other files via forvard declaration

Question 41

External variables

Answer 41

Global variables with external linkage

Question 42

Making global variables external

Answer 42

By using the extern keyword

Question 43

External keyword

Answer 43

Has 2 meanings * gives a variable external linkage * acts as forward declaration for external variable defined somwhere else

Question 44

Defining non-const global variables

Answer 44

Do not use extern

Question 45

Function forward declaration

Answer 45

It does not need the extern keyword

Question 46

Variable forward declaration

Answer 46

It needs extern keyword to differentiate variables definitions and forward declarations

Question 47

Static initialization of global variables

Answer 47

With const_expr initializers are initialized to those values, those without are zero initialized

Question 48

Dynamic initialization of global variables

Answer 48

Are initialized with non-constexpr initializers

Question 49

Order of initialization of global variables

Answer 49

They are initialized as they are defined

Question 50

Declaring global constants as internal variables

Answer 50

* create a header file to hold the constants * inside the file define a namespace * add the constants (constexpr) inside the namespace * include file wherever

Question 51

Optimazing away

Answer 51

Refers to any process where the compiler optimizes the performance of your program by removing things in a way that doesn't affect the output of the program

Question 52

Downsides of global constants as internal variables

Answer 52

* changing a single constant value would require recompiling every file that includes the constant header * if a constants are large in size and can't be optimized away, it can use a lot of memory

Question 53

Turning constants into extern variables

Answer 53

Use const instead constexpr, with the use of a g_ prefix

Question 54

Downsides of external variables

Answer 54

* the constants are compile-time constants | * the compiler may not be able to optimize this

Question 55

Inline variable

Answer 55

Variable that is allowed to be dedined in multiple files without violating the one definition rule, it has external linkage

Question 56

Restrictions of inline variable

Answer 56

* all definitions of the inline variable must be identical | * the inline variable definitionmust be present in any file that uses the variable

Question 57

Downsides of non-const global variables

Answer 57

* their value can be changed by any function that is called * you might have to look through the entire program to understand their usage * they make your program less modular and flexible

Question 58

Advantiges of local variables

Answer 58

* other functions can't affect them directly * declaring them as close to where are used as possible (minimizes the amount of code you need to look trough)

Question 59

Modularity

Answer 59

Function that utilizes nothing but its parameters and has no side effects

Question 60

When to use non- const global variables

Answer 60

* a log file, where you dump error or debug information * when there should be only one of the thing the variable represents or it's use should be umbigous troughout the program

Question 61

How to use global variables

Answer 61

* prefix all non-namespaced global variables with g or g_ or put them in namespace * variable should be only accesed from within the file its declared in * provide external global "access functions" to work with the variable * pass the variable as argument, instead using it directly into the function