Fundamentals

Question 0

What is the difference between a statement, expression, and function?

Answer 0

A statement is a single instruction terminated with a semicolon.

An expression is a mathematical entity which evaluates to a value; often used within statements.

A function is a collection of statements designed to perform a specific job.

Question 1

What are libraries?

Answer 1

Groups of functions packaged for reuse

Question 2

What is an l-value?

Answer 2

A value that has an address in memory. Examples are variables. The ‘l’ refers to the fact that these are the only values which can be on the left side of an assignment statement

Question 3

What is an r-value?

Answer 3

Any value that can be assigned to an l-value and always evaluates to produce a single value.

Question 4

What happens to the value already in memory when that memory is allocated?

Answer 4

The preexisting value is NOT overwritten, which is part of why uninitialized variables yield seemingly random ‘undefined’ results.

Question 5

What does the type specification tell the compiler when declaring a variable?

Answer 5

How much memory to allocate.

Question 6

What is the difference between a literal and a variable?

Answer 6

A literal always evaluates to itself, while a variable evaluates to its held value.

Question 7

What is the difference between a unary and binary operator?

Answer 7

A unary operator acts on one operand (i.e. the ‘-‘ symbol when specifying a negative number), while a binary operator acts on two operands (i.e. the ‘-‘ symbol when used to subtract one number from another)

Question 8

What is a forward declaration?

Answer 8

Declaring a variable before it is used/initialized.

Question 9

What is a function prototype, an what must it have

Answer 9

A function prototype declares the function but does not implement it. It contains the name of the function along with the parameter types and return types. Parameter names are optional but recommended. They should be declared near the top of a file.

Question 10

What will happen if a function is defined but not implemented and then called?

Answer 10

The program will compile without error, but the linker will produce the error because it cannot find the function implementation and cannot resolve the function call.

Question 11

How can a .cpp file become aware of functions in other .cpp files

Answer 11

A .cpp file can become aware of functions in other .cpp files by including a forward declaration of that function.

Question 12

What is a header file?

Answer 12

Contains only function declarations and NOT implementations. For example, iostream.h declares ‘cout’ (so the compiler is happy) but the implementation is within the runtime support library, which is automatically linked to the program by the linker.

Question 13

What does a library consist of?

Answer 13

A header file with declarations of public functions and a precompiled object that contains all of the implementation code in machine language.

Question 14

Why is having a precompiled library beneficial?

Answer 14

They rarely change, and the constant need to recompile them is a waste of time. It also hides source code, which is important for intellectual properties.

Question 15

T/F: header files should contain implementations.

Answer 15

F; header files should contain only declarations and prototypes, unless the implementation is extremely trivial.

Question 16

What are some rules about header files?

Answer 16

They should always include header guards, not declare variables unless they are constants, be independent and have a specific job relative to a corresponding .cpp file, and should include as few other headers as possible.

Question 17

Why do some standard library headers have the .h extension while some do not?

Answer 17

Those without extensions are newer, post standardization, and move their functions into the ‘std’ namespace. Those with .h extensions are older and allow for backwards compatibility.

Question 18

What does the #include directive do?

Answer 18

It inserts the contents of a file at the point of the directive.

Question 19

What is the #define directive?

Answer 19

define identifier replacement

It is a macro with the syntax:

The identifier should be in all caps and use snake_casing

Question 20

What is the #undef directive?

Answer 20

It undefines a macro

Question 21

What is the syntax of a conditional compilation?

Answer 21

#ifdef
#define
  //code here
#endif

Question 22

What is a header guard?

Answer 22

It prevents a file from being included more than once and wraps the entire header file.

It used #ifndef to see if a file has not been defined yet. It uses the following syntax:

#ifndef FILENAME_H
#define FILENAME_H
  //declarations here
#endif

Question 23

What is a good programming workflow?

Answer 23

1) define the problem
2) define the target (user, system, requirements, etc.)
3) break down the complex problem into simplest tasks using a top-down hierarchy
4) identify the sequence of events
5) figure out data inputs and outputs for each task by declaring prototypes
6) write the task details by implementing the functions
7) connect data inputs and outputs in a logical and readable way

Question 24

What are some other programming pointers?

Answer 24

• KISS
• add features over time
• focus on one area at a time
• test each piece of code as you go