// Lab 5 Lesson


#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;

int main()
{

// ------------------------ Review If/Else ---------------------------------

	// Switch statements function similarly to an if...else statement.
	// The following can be rewritten as a switch statement.
	
	char letter_grade;
	float GPA;

	letter_grade = 'B';

	// IF-ELSE statement to determine letter grade
	if(letter_grade == 'A'){
		GPA = 4.0;
	}
	else if (letter_grade == 'B'){
		GPA = 3.0;
	}
	else if (letter_grade == 'C'){
		GPA = 2.0;
	}
	else if (letter_grade == 'D'){
		GPA = 1.0;
	}
	else if (letter_grade == 'F'){
		GPA = 0.0;
	}
	else{
		cout << "invalid input" << endl;
	}

	cout << "Using IF Statements : "
			<< setprecision(1) << fixed << GPA << endl;

			
// ------------------------ Switch Statement ----------------------------------

	// Switch Statement can do the same thing
	
	// Switch syntax is as follows:
        
	// switch (expression){
	//     case  constant-expression: 
	//         // statements
    //         break;
	// }
	
	// The switch's expression is compared to each case's expression.
	// if the expressions are equal to eachother it will execute any statements
	// that follow the case, until hitting a break statement. Break statements
	// tell the program to leave the switch statement and continue after it.
	
	// This switch statement does the same thing as the above IF-ELSE IF code.

	switch (letter_grade){
	case 'A':
		GPA = 4.0;
		break;		// break statements signal to leave the switch statement
	case 'B': 		
		GPA = 3.0;
		break;
	case 'C':
		GPA = 2.0;
		break;
	case 'D':
		GPA = 1.0;
		break;
	default:        // default is like an else statement
		cout << "invalid input" << endl;
		break;
	}

	cout << "Using Switch Statement : "
			<< setprecision(1) << fixed << GPA << endl;

			
// ------------------ Multiple Cases in a Single Break ------------------------

	// What if you wanted to allow the user input to not be case sensitive?
	// We can have multiple cases assigned to execute the same code. In the 
	// following snippet, both an upper case and lower case letter will execute
	// the same thing. 

	letter_grade = 'b';

	switch (letter_grade){
	case 'A': 	// same as if(letter_grade == 'A' || letter_grade == 'a')
	case 'a':
		GPA = 4.0;
		break;
	case 'B':
	case 'b':
		GPA = 3.0;
		break;
	case 'C':
	case 'c':
		GPA = 2.0;
		break;
	case 'D':
	case 'd':
		GPA = 1.0;
		break;
	default:    //default is like an else statement
		cout << "invalid input" << endl;
		break;
	}

	cout << "Using Lower Case Input : "
			<< setprecision(1) << fixed << GPA << endl;

			
// ----------------- Disadvantages of a switch statement ---------------------_

	// Consider the following if...else statement
	
	int num = 85;
	if(num <= 89 &&  num >= 80){
		cout << "Your letter grade is a B (If Statement)" << endl;
	}else{
		cout << "out of range" << endl;
	}

	// you cannot easily implement a range with a switch statement.
	// the only possible way to duplicate the above if...else Statement is
	// to list each case out individually. Both if...else statements and switch
	// statements haves pros and cons which should be weighed before
	// implementing one or the other. 

	switch(num){
		case 89:
		case 88:
		case 87:
		case 86:
		case 85:
		case 84:
		case 83:
		case 82:
		case 81:
		case 80:
			cout << "your letter grade is a B (Switch Statment)" << endl;
			break;
		default:
			cout << "out of range" << endl;
			break;
	}

	
// ------------------------ Switch Example ----------------------------------

	// Another example of a case statement
	// Can you understand it? As you can see, as programs
	// get more complex using good style is crucial for 
	// readability.
	
	// This is another example where using if...else statements
	// might be better as it would likely be more readable. 

	const double PI = 3.14159;

	int choice_A;
	int choice_B;
	double total;

	cout << "\n\nWelcome to my shape calculator!" << endl << endl
			<< "Please select one of the following" << endl
			<< "1. Circle" << endl
			<< "2. Square " << endl;

	cin >> choice_A;

	switch(choice_A){
		case 1:
			double radius;
			cout << "You have selected Circle!" << endl << endl
					<< "Please enter the radius of your circle" << endl;
			cin >> radius;
			cout << "Please select one of the following" << endl
					<< "1. Area" << endl
					<< "2. Circumference" << endl;
			cin >> choice_B;

			switch(choice_B){
				case 1:
					total = PI * pow(radius, 2.0);
					cout << "The Area is " << total << endl;
					break;
				case 2:
					total = PI * 2 * radius;
					cout << "The Circumference is " << total << endl;
					break;
				default:
					cout << "invalid input. Terminating the program." << endl;
					break;
			}
			break;

		case 2:
			double length;
			cout << "You have selected Square!" << endl << endl
					<< "Please enter the length of a side." << endl;
			cin >> length;
			cout << "Please select one of the following" << endl
					<< "1. Area" << endl
					<< "2. Perimeter" << endl;
			cin >> choice_B;

			switch(choice_B){
				case 1:
					total = pow(length, 2.0);
					cout << "The Area is " << total;
					break;
				case 2:
					total = length * 4;
					cout << "The Perimeter is " << total;
					break;
				default:
					cout << "invalid input. Terminating the program." << endl;
					break;
			}
			break;

		default:
			cout << "Invalid input. Terminating the program." << endl;
			break;
	}

// ----------------------------------------------------------------------------


	return 0;
}