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| Calculator - Step 2.4 Process the rest of the buttons |
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Objective for this step
In this step, we will finish up processing the rest of the buttons, including "C", "CE", "BackSpace" and "." (the decimal point).
The Code
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| <?php
class Calculator{
var $operator = '';
var $stack = array();
var $is_entering_number = 0;
// constructor
function Calculator() {
}
function main() {
$this->setup_window();
$this->setup_layout();
$this->window->show_all(); // display the calculator
Gtk::main(); // and let's go!
}
function setup_window() {
$this->window = new GtkWindow();
$this->window->set_size_request(200, 240);
$this->window->connect_simple('destroy', array('Gtk','main_quit'));
}
function setup_layout() {
// setup a vbox to hold display and buttons
$vbox = new GtkVBox();
$this->window->add($vbox);
// setup display
$this->display = new GtkEntry();
$this->display->set_alignment(1.0); // right-justified
$this->display->set_editable(false); // for display only
$vbox->pack_start($this->display);
// the button labels
$button_label = array(
array('BackSpc', 'CE', 'C'),
array('7', '8', '9', '/', 'sqrt'),
array('4', '5', '6', '*', '%'),
array('1', '2', '3', '-', '1/x'),
array('0', '+/-', '.', '+', '=')
);
// setup the buttons
for ($j=0; $j<5; ++$j) {
$hbox = new GtkHBox();
$vbox->pack_start($hbox); // use a hbox to hold each row of buttons
for ($i=0; $i<5; ++$i) {
if ($j==0 && $i>2) continue; // first row contains only 3 buttons
$button = new GtkButton($button_label[$j][$i]);
$button->set_size_request(40, 32); // set the size
$button->connect('clicked', array(&$this, "on_button"));
$hbox->pack_start($button);
}
}
}
// process button click
function on_button($button) {
$value = $button->child->get_text();
$t = ($value=='1/x');
echo "button_click: $value ($t)\n";
if (preg_match("/^([0-9]|\.)$/", $value)) { // include also the decimal point
$number = array_pop($this->stack);
if (preg_match("/^([0-9]|\.)+$/", $number)) {
$number .= $value;
} else {
if ($number!='') array_push($this->stack, $number);
$number = $value;
}
array_push($this->stack, $number);
$this->display->set_text($number);
} elseif (preg_match("/^(\+|-|\*|\/|=){1}$/", $value)) { // perform binary operations
if (count($this->stack)<3) {
array_push($this->stack, $value);
} else {
$number2 = array_pop($this->stack);
$operator = array_pop($this->stack);
$number1 = array_pop($this->stack);
switch ($operator) {
case '+': $result = $number1 + $number2; break;
case '-': $result = $number1 - $number2; break;
case '*': $result = $number1 * $number2; break;
case '/': $result = $number1 / $number2; break;
}
$this->display->set_text($result);
array_push($this->stack, $result);
if ($value!='=') array_push($this->stack, $value);
}
//process unary operators
} elseif ($value=='1/x' || $value=='sqrt' || $value=='%' || $value=='+/-') {
if (count($this->stack)>=1) {
$number = array_pop($this->stack);
switch ($value) {
case '1/x': $result = 1/$number; break;
case 'sqrt': $result = sqrt($number); break;
case '%': $result = $number / 100; break;
case '+/-': $result = -$number; break;
}
$this->display->set_text($result);
array_push($this->stack, $result);
}
} elseif ($value=='C') {
$this->stack=array(); // clears the stack
$this->display->set_text('0');
} elseif ($value=='CE') {
if (preg_match("/^([0-9]|\.)+$/", end($this->stack))) { // make sure its a number
$number = array_pop($this->stack); // clears the number on top of stack
$this->display->set_text('0');
}
} elseif ($value=='BackSpc') {
if (preg_match("/^([0-9]|\.)+$/", end($this->stack))) { // make sure its a number
$number = array_pop($this->stack); // get the number
$number = substr($number, 0, strlen($number)-1); // remove the right-most digit
$this->display->set_text($number);
array_push($this->stack, $number); // push it back to stack
}
}
$this->show_stack(); // show current stack
}
// prints the current stack content
function show_stack() {
echo "current stack content:\n";
for ($i=count($this->stack)-1; $i>=0; --$i) {
echo "stack[$i] = {$this->stack[$i]}\n";
}
echo "\n";
}
}
$cal = new Calculator(); // cerate a new calculator
$cal->main(); // let's run it!
?> |
Explanation
- '.' - just treat it like a number
- 'C' - clears the entire stack
- 'CE' - clears only the most recent number by popping the number off the top of the stock
- 'BackSpace' - removes the rightmost digit of the number on the top of the stack
What's Next
We have finished processing all the buttons. We will deal with keyboard input in the next step.
Links
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