Week 2 - Day 3 - Conditional Logic

logic.php

<?php
/**
 * Mathematical Comparison Operators
 * x > y,   is x greater than y?
 * x >= y,  is x greater than OR equal to y?
 * x < y,   is x less than y?
 * x <= y,  is x less than OR equal to y?
 * 
 * Logical Comparison Operators
 * x == y,  does x have the same value as y?
 * x != y,  do x and y have different values?
 * x === y, do x and y have the same value and data type?
 * x !== y, do x and y have a different value or data type?
 * x && y,  are x AND y true?
 * x || y,  is x OR y true?
 * x ^ y,   is x or y true, and are x and y both not true?
 * 
 */
 
// simple if statement
$firstVariable = 8;

if( $firstVariable < 10 ){              // is $firstVariable less than 10?
    echo 'True';
}
// what if it isn't?
else {
    echo 'False';
}

// multi step if statement
$secondVariable = 10;

if( $secondVariable < 10 ){             // is $secondVariable less than 10?
    echo 'Less than 10';
} else
if( $secondVariable == 10 ){            // is $secondVariable equal to 10?
    echo 'Equal to 10';
} else {
    echo 'It must be greater than 10';
}

// multiple condition if statement
if( $firstVariable < $secondVariable && $secondVariable == 10 ){
    // is $firstVariable LESS THAN $secondVariable, and $secondVariable is equal to 10?
    echo 'Both conditions are true!';
}

// using a switch statement to compare multiple answers
$thirdVariable = 9;

// the question being asked: what is $thirdVariable, and what to do with that value?
switch( $thirdVariable ){
    case 7:
        echo 'It must be seven!';
        break;                          // don't forget the break!
    case 8:
        echo 'It must be eight!';
        break;
    case 9:
        echo 'It must be nine!';
        break;
    default:
        echo 'I have no clue what it is!';
}

// using a switch with combined cases
$fourthVariable = 7;

switch( $fourthVariable ){
    case 2:
    case 4:
    case 6:
    case 8:
        echo 'The number must be even!';
        break;
    case 1:
    case 3:
    case 5:
    case 7:
    case 9:
        echo 'The number has to be odd!';
    default:
        echo 'Can not compute!';
}

// being able to minimize that switch statement using modulus and an if statement
if( $fourthVariable % 2 == 0 ){
    // we ask if the remainder of $fourthVariable divided by 2 is equal to 0
    // if it is 0, it is an even number
    echo 'The number must be even!';
}else {
    // else it is an odd number
    echo 'The number must be odd!';
}

?>

"x ^ y, is x or y true, and are x and y both not true?"

Should probably be

"x ^ y, is x or y true, and are x and y not both true?"

otherwise it reads as a logical paradox (x or y needs to be true, but they also need to both be not true).