Repaso: calculadora simple

Parte de la sección Programación Orientada a Objetos del Journey de PHP de Coddy. Lección 9 de 91.

Desafío

Intermedio

Construye una clase Calculator completa en calculator.php que demuestre todos los conceptos de POO que has aprendido. El archivo driver.php importará y probará tu clase.

Tu clase Calculator debe incluir:

Propiedad: Una propiedad public $result para almacenar el total acumulado
Constructor (__construct): Inicializa $result a 0 e imprime "Calculator ready"
Destructor (__destruct): Imprime "Calculator shutting down"
Métodos que utilicen $this para actualizar y devolver el resultado:
- add($number): suma el número al resultado
- subtract($number): resta el número del resultado
- multiply($number): multiplica el resultado por el número
- divide($number): divide el resultado entre el número mediante división entera (intdiv). Si el número es 0, imprime "Error: Division by zero" y devuelve el resultado sin cambios
- clear(): restablece el resultado a 0
- getResult(): devuelve el resultado actual

Todos los métodos aritméticos deben devolver el nuevo resultado después de la operación.

Ejemplo de uso:

require_once 'calculator.php';

$calc = new Calculator();  // prints: Calculator ready
$calc->add(5);             // result becomes 5
$calc->multiply(3);        // result becomes 15
$calc->subtract(2);        // result becomes 13
$calc->divide(0);          // prints: Error: Division by zero (result stays 13)
$calc->divide(2);          // result becomes 6 (integer division)
$calc->clear();            // result becomes 0
// When script ends: prints Calculator shutting down

Pruébalo tú mismo

<?php
require_once 'calculator.php';

$testCase = trim(fgets(STDIN));

if ($testCase == "constructor_test") {
    $calc = new Calculator();
    echo "Initial result: " . $calc->getResult() . "\n";
    echo "Calculator created successfully\n";

} elseif ($testCase == "addition_test") {
    $calc = new Calculator();
    $result1 = $calc->add(10);
    echo "After adding 10: " . $result1 . "\n";
    $result2 = $calc->add(5);
    echo "After adding 5: " . $result2 . "\n";
    echo "Final result: " . $calc->getResult() . "\n";

} elseif ($testCase == "subtraction_test") {
    $calc = new Calculator();
    $calc->add(20);
    $result1 = $calc->subtract(8);
    echo "After subtracting 8 from 20: " . $result1 . "\n";
    $result2 = $calc->subtract(2);
    echo "After subtracting 2: " . $result2 . "\n";
    echo "Final result: " . $calc->getResult() . "\n";

} elseif ($testCase == "multiplication_test") {
    $calc = new Calculator();
    $calc->add(5);
    $result1 = $calc->multiply(4);
    echo "After multiplying by 4: " . $result1 . "\n";
    $result2 = $calc->multiply(2);
    echo "After multiplying by 2: " . $result2 . "\n";
    echo "Final result: " . $calc->getResult() . "\n";

} elseif ($testCase == "division_test") {
    $calc = new Calculator();
    $calc->add(100);
    $result1 = $calc->divide(4);
    echo "After dividing by 4: " . $result1 . "\n";
    $result2 = $calc->divide(5);
    echo "After dividing by 5: " . $result2 . "\n";
    echo "Final result: " . $calc->getResult() . "\n";

} elseif ($testCase == "division_by_zero_test") {
    $calc = new Calculator();
    $calc->add(50);
    echo "Initial value: " . $calc->getResult() . "\n";
    $result = $calc->divide(0);
    echo "Result after division by zero: " . $result . "\n";
    echo "Value unchanged: " . $calc->getResult() . "\n";

} elseif ($testCase == "clear_test") {
    $calc = new Calculator();
    $calc->add(25);
    $calc->multiply(3);
    echo "Before clear: " . $calc->getResult() . "\n";
    $result = $calc->clear();
    echo "After clear: " . $result . "\n";
    echo "Current result: " . $calc->getResult() . "\n";

} elseif ($testCase == "comprehensive_test") {
    $calc = new Calculator();
    $calc->add(10);
    $calc->multiply(3);
    $calc->subtract(5);
    $calc->divide(5);
    echo "After sequence of operations: " . $calc->getResult() . "\n";
    $calc->divide(0);
    echo "After division by zero attempt: " . $calc->getResult() . "\n";
    $calc->clear();
    $calc->add(100);
    echo "After clear and add 100: " . $calc->getResult() . "\n";

} else {
    echo "Unknown test case\n";
}