learningPHP: Chapter-3

3_logic.php

<?php
// Chapter - 3: Exercises

// Question-1

// 1. Without using a PHP program to evaluate them, determine whether each of
// these expressions is true or false:
// a. 100.00 - 100
// b. "zero"
// c. "false"
// d. 0 + "true"
// e. 0.000
// f. "0.0"
// g. strcmp("false","False")
// h. 0 <=> "0"

// Answer-1

// 1. false
// 2. true
// 3. true
// 4. false
// 5. false
// 6. true
// 7. true
// 8. false

// Question-2

// 2. Without running it through the PHP engine, figure out what this program prints:
// $age = 12;
// $shoe_size = 13;
// if ($age > $shoe_size) {
// print "Message 1.";
// } elseif (($shoe_size++) && ($age > 20)) {
// print "Message 2.";
// } else {
// print "Message 3.";
// }
// print "Age: $age. Shoe Size: $shoe_size";

// Answer-2

// Message 3.Age: 12. Shoe Size: 14

// Question-3

// 3. Use while() to print a table of Fahrenheit and Celsius temperature equivalents
// from –50 degrees F to 50 degrees F in 5-degree increments. On the Fahrenheit
// temperature scale, water freezes at 32 degrees and boils at 212 degrees. On the
// Celsius scale, water freezes at 0 degrees and boils at 100 degrees. So, to convert
// from Fahrenheit to Celsius, you subtract 32 from the temperature, multiply by 5,
// and divide by 9. To convert from Celsius to Fahrenheit, you multiply by 9, divide
// by 5, and then add 32.

// Answer-3

$f = -50;
while ($f <= 50) {
    $c = ($f - 32) * (5 / 9);
    printf("%d degrees F = %d degrees C\n", $f, $c);
    $f += 5;
}

// 4. Modify your answer to Exercise 3 to use for() instead of while().

// Answer-4

for ($f = -50; $f <= 50; $f += 5) {
    $c = ($f - 32) * (5 / 9);
    printf("%d degrees F = %d degrees C\n", $f, $c);
}