Introduction to OOP - Modular Programming

What is modular programming

breaking our program into seperate files and functions, each handling a specific task

What are the 3 main benefits of modular programming

readability, reusability, and maintainability

what is readability?

code is easier to understand

what is reusability?

using the same function in multiple programs

what is maintainability?

fixing bugs in one module without effecting the whole program

What goes in header files (.h) ?

types, functions, classes, constant declarations, macros which can be used in multiple files

What are header guards?

#ifndef FILENAME_H
#define FILENAME_H

#endif

what do header guards do?

prevent the file from being included multiple times in the same program

what is extern

used to declare variables/functions that exist in another file

what goes in implementation files (.cpp)?

function and class definitions

what goes in the main file (main.cpp) ?

main() function

include the header file and call the functions

what are namespaces?

containers for related identifiers (functions, variables, classes) that helps prevent naming conflicts

what is the C++ standard namespace?

standard C++ library is defined inside the namespace std::

std::cout << "Hello";

what is a using directive?

using namespace std;

• used to bring names from a namespace into the current scope

• this avoids writing std:: everywhere, but can cause naming conflicts in large programs

how to define namespaces?

namespace english {
   int x = 2;
}
// english is the scope name

you define the namespace with the namespace keyword, then declare your identifiers inside its block

how to access elements

english::x;

outside that block, you refer to them using the scope resolution operator :: e.g. namespace::id

what is the compilation process?

process that turns source code into machine code

creates an executable that can run independently of your compiler/IDE

what is source code?

regular text file or multiple text files

What are the steps of compilation?

preprocessing, compilation, and linkage

what does the preprocessor do?

adds contents from included files according to directives

what does the compiler do?

translates the source into an object file containing machine code

what does the linker do

merges together all object code files into an executable

What are some common syntactic errors?

• normally results in “wrong results”

• mixing = and == or & and &&

• uninitialized variable

• infinite or off by one iterations

what is =

assignment operator

what is the assignment operator used for?

// used to store/change a value in a variable 
int x = 5; 
// meaning: put/store 5 in x

what is ==

equality comparision operator

what is the equality comparision operator used for?

// used to check if two values are equal 
if (x == 10) 
// meaning: Is x equal to 10? 
// this returns true or false

what is &&

logical AND

what is the logical AND used for?

// used to check if both conditions are true
if (x > 0 && y > 0)
// meaning: x is greater than 0 and y is greater than 0
// both must be true for the whole condition to be true

what is &

address operator

what is the address operator used for?

// 1. & as address-of operator
// gets the memory address of a variable
int x = 5;
std::cout << &x;
// meaning: give me the memory address of x

// 2. & in parameters -> reference
void change (int &num)
// meaning: num is a reference to the original variable
// changes affect the real variable

What are the common execution errors?

• normally results in “crashes”

• attempting to access invalid memory

• division by zero

• unhandled exceptions