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C++ BASICS

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OPEN WEBSITE

Go to https://www.online-cpp.com/

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REVIEW DEFAULT FILE

Comment
Include
Semi-colons
Main plus curly brackets
cout
return
Using namespace

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REMOVE USING NAMESPACE

Remove using namespace and make it build
Run it
Duplicate the line and change the text in between the “”
Run it

(add std:: to the cout line)

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ADD END OF LINE TO EACH LINE

Add << std::endl between the last “ and the ; on each cout line
Run it

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ADD USING STD::ENDL AND STD::COUT

Add before int main():

using std::cout;
using std::endl;

Remove the std:: from before cout and endl
Run it

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VARIABLES

int
unsigned int
double
float
bool
Define a variable of each type and initialize it to any valid value.
Print it using cout
Run it
Try giving it invalid values or removing the semi-colons to see what happens

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MATH

Addition – Create a variable that is your double plus 10.5
Subtraction – Create a variable that is your double minus 3.5
Multiplication – Create a variable that is your double times 3.5
Division – Create a variable that is your double divided by 2.5
Print your new values
Run it
Do the same things with your floats, ints and unsigned ints
What happens if instead of hard coding the value you use constexpr?
What happens if you divide by 0?

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SPECIAL MATH FUNCTION

++ increment
-- decrement
Pre vs. Post increment/decrement operations
Comment out previous code changes (everything between the first curly bracket and return 0; in main)

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SPECIAL MATH FUNCTION

Add the following code inside main

int a = 21;

int c;

c = a++;

cout << “==>> a: “ << a << endl;

cout << “==>> c: “ << c << endl;

c = ++a;

cout << “==>> a: “ << a << endl;

cout << “==>> c: “ << c << endl;

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FOR LOOPS

There are other types of loops, but we’ll focus on this one for now
Create

for (auto i=0; i<3; ++i)

{

cout << “value = “ << i << endl;

}

Run it

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METHODS

Comment out previous code changes (everything between the first curly bracket and return 0; in main)
Create a method named int PrintFactorial(int value)
Create an int variable output and set it equal to 1
Create a for loop that loops from 1 to the value passed
Inside the loop output *= the loop index
Return output
Call this method from main and print the value returned
Run it

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METHODS

#include<iostream>

#include "Factorial.h“

using std::cout;

using std::endl;

int main()

{

constexpr int value = 3;

auto fact = new Factorial();

cout << "The factorial for " << value << " is " << fact->Calc(value) << endl;

return 0;

}

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METHODS

#include<iostream>

#include "Factorial.h“

int Factorial::Calc(int value)

{

auto output = 1;

for (auto i=1; i<= value; ++i)

{

output *= I;

}

return output;

}

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METHODS

#pragma once

class Factorial

{

Factorial() = default;

~Factorial() = default();

int Calc(int value);

};

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METHODS - CONTINUED

Switch your factorial code to use a decrement instead of a increment

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METHODS – PASS BY VALUE

Variable is passed by type
Value is copied to the method, so it isn’t altered in the caller

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METHODS – PASS BY VALUE

Create a method named ScaleValue that takes in two double values and returns void
The first parameter should be the value and the second the scale factor
Inside the method set the value *= scaleFactor;
Print the value and the scale factor inside this method
Call it from main and print the values as well.
Run it

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METHODS – PASS BY REFERENCE

Modify the first parameter to be an integer reference (double&)
What is different when you run it?

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METHODS – PASS BY POINTER

Modify the first parameter to be pointer to an integer (int*)
Inside the method, you need to dereference the pointer to get to the integer to do the math (*value *= scaleFactor;)
What is different when you run it?

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METHODS – COMPARISON OF VARIABLE PASSING

Pass by value when the value doesn’t change (particularly simple variables)
Pass by reference when it needs to change (or const reference if it is a complex variable type when it isn’t changing)
Pass by pointer when you need to