Mastering Glade for PHP-GTK2
PHP-GTK2 Cookbook Vol.2
PHP-GTK2 Cookbook Vol.1
Intro to Glade for PHP-GTK2
PHP-GTK2 Demystified
PHP-GTK ExplorerYour "secret weapon" for learning, exploring, understanding and mastering PHP-GTK2!
[Free Download Here]
|
|
|
| Calculator - Step 3. Validation Checks |
|
Objective for this step
In this step, we will try to "foolproof" our calculator by putting in some validation checks .
The Code
Note: If you have installed php-gtk2 using Gnope Installer on Windows, and if running the sample code below gives you warning that the Symbolic names for keys (e.g. Gdk::KEY_Return) is not defined, you might want to update your php-gtk2 with the latest php-gtk2.dll available here. Simply download the php-gtk2.dll and replace the copy in the folder php-gtk2\ext. The latest compilation has put in the Symbolic names for keys listed here. 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
24
25
26
27
28
29
30
31
32
33
37
38
39
45
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
70
71
72
73
74
75
76
77
78
79
80
81
82
83
86
87
88
89
94
95
96
97
98
99
100
101
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
| <?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'));
$this->window->connect('key-press-event', array(&$this, "on_keypress"));
}
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();
echo "button_click: $value\n";
$this->process_input($value);
}
// process keyboard input
function on_keypress($widget, $event) {
$keyval = $event->keyval;
$value = chr($keyval); // get the ASCII equivalent
if (preg_match("/[0-9\+\-\*\/\.=]/", $value) || $keyval==Gdk::KEY_Return || $keyval==Gdk::KEY_BackSpace) {
if ($keyval==Gdk::KEY_Return) $value='=';
if ($keyval==Gdk::KEY_BackSpace) $value='BackSpc';
$this->process_input($value);
$this->display->set_position(-1); // move the cursor to the end of display
}
}
// process input
function process_input($value) {
if (preg_match("/^([0-9]|\.)$/", $value)) {
$number = array_pop($this->stack);
if (preg_match("/^([0-9]|\.)+$/", $number)) {
if ($value=='.') {
if (strpos($number,'.')===false) $number .= $value; // note 1
} else {
$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) {
if (preg_match("/^([0-9]|\.)+$/", end($this->stack))) // note 2
if ($value!='=') // note 3
array_push($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();
$this->display->set_text('0');
} elseif ($value=='CE') {
if (preg_match("/^([0-9]|\.)+$/", end($this->stack))) {
$number = array_pop($this->stack);
$this->display->set_text('0');
}
} elseif ($value=='BackSpc') {
if (preg_match("/^([0-9]|\.)+$/", end($this->stack))) {
$number = array_pop($this->stack);
$number = substr($number, 0, strlen($number)-1);
$this->display->set_text($number);
array_push($this->stack, $number);
}
}
$this->show_stack(); // show current stack
}
// prints the current stack content
function show_stack() {
echo "current stack content:\n";
for ($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
Below are some of the validation checks that we have put in:
- don't allow two decimal points e.g. 1.2.3
- + - * / - will only be added to stack if top of stack is a number
- if there is only one number on stack, and the user press '=', the '=' should be go to stack.
There are many more other validation checks that need to put in place if you really want to make this calculator "foolproof". We won't go into all since the focus here is php-gtk2 as oppose to calculator.
Links
|
Search PHP-GTK2 Manual
Full-text search on php-gtk2 manual
|
