C++

Question 1

What is the keyword to add to prevent reassignment?

Answer 1

const

Question 2

How to instantiate an array? How to access elements in the array?

Answer 2

int array[ARRAY_CAPACITY];
array[INDEX];

Question 3

What are statements that start with #?

Answer 3

Preprocessor directives

Question 4

What happens to the preprocessor directives when we compile a C++ program?

Answer 4

When we compile, the first step is preprocessing. The preprocessor scans the cpp file for any lines starting with #. It replaces these lines with the actual content of the included file. The output of the preprocessor is a modified version of the source code.

Question 5

Does the preprocessor need to understand C++ semantics?

Answer 5

No, all it does is text-based manipulations. It just modifies the code before the compiler sees it.

Question 6

Why is it beneficial to have a header file separate from the source code?

Answer 6

The source code will be compiled into a library .o. It allows other programs to use the functions by including the header file only. Since the library implementation is already compiled into an object file, it saves time during compilation.

Question 7

What is a library?

Answer 7

A collection of precompiled object files packaged together.

Question 8

What does it mean to compile into a library?

Answer 8

1. Compile a .cpp file into an object file
2. Package those object files into a library

Question 9

Why is having a library useful?

Answer 9

The library can be reused across programs. The developer does not have to distribute the source code and recompile every time, only the library file.

Question 10

What is the difference between a static library vs a dynamic/shared library?

Answer 10

When you link a program with a static library, all the required code is copied into the final executable. When you use a dynamic library, the library code is not copied. The executable refers to the library, which is loaded into memory at runtime.

Question 11

Would there be errors if you include the same header file multiple times into your program (either directly or indirectly)?

Answer 11

Yes

Question 12

What is the directive to prevent a header file from being included multiple times in one cpp file?

Answer 12

pragma once

Question 13

What are include guards? How to write them?

Answer 13

ifndef MYHEADER_H

They are a traditional way to prevent multiple inclusions.

#define MYHEADER_H
…
…
#endif

Question 14

What does a cpp file need to have to be compiled into an executable?

Answer 14

It needs a int main(), if not, it can only be compiled into an object file.

Question 15

Does a main() always return an int?

Answer 15

Yes, it is always defined as int main() and returns an int. The return value serves as an exit status, so it always expects 0, indicating a successful execution of the program.

Question 16

Give a version of int main() that takes arguments.

Answer 16

int main(int argc, char* argv[])

argc is the argument count (includes program name)
argv is argument vector

Question 17

What are variables defined in functions, classes, elsewhere called respectively?

Answer 17

Functions: local
Classes: member
Elsewhere: global

Question 18

What are functions defined in classes, elsewhere called?

Answer 18

Classes: member
Elsewhere: global

Question 19

What is static used for local variables, global variables, functions, classes?

Answer 19

Local variables: makes the variable only accessible within the function and the value persists between function calls
Global variables: makes the variable local to the file
Functions: restrict the function to file scope (only visible to other functions within the same file)
Classes: class scope (shared across all objects of the class)

Question 20

How to define a namespace?

Answer 20

namespace i_am_lia {
…
}

Question 21

How to access variables outside of the namespace?

Answer 21

i_am_lia::sleeping();
using namespace i_am_lia;

Question 22

Is using namespace used in production code?

Answer 22

No