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September 20, 2012 14:47
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Calculator Example (v2)
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| <?php | |
| /* ====================================================== | |
| PHP Calculator example using "sticky" form (Version 2) | |
| ====================================================== | |
| - uses a dropdown select box to select operation | |
| - does very basic validation | |
| - uses a function to calculate result | |
| - traps a devide by zero error | |
| - author : p-chatterjee, sept.2012 | |
| */ | |
| // function to calculate and return result | |
| function calculate($x, $y, $op) { | |
| // calculate $prod using switch (case) statement | |
| switch($op) { | |
| case '+': | |
| $prod = $x + $y; | |
| break; | |
| case '-': | |
| $prod = $x - $y; | |
| break; | |
| case '*': | |
| $prod = $x * $y; | |
| break; | |
| case '/': | |
| if ($y == 0) {$prod = "∞";} | |
| else {$prod = $x / $y;} | |
| } | |
| // return the result | |
| return $prod; | |
| } | |
| // declare all variables | |
| $x = 0; | |
| $y = 0; | |
| $prod = 0; | |
| $op = ''; | |
| // grab the form values from $_GET hash | |
| extract($_GET); | |
| ?> | |
| <html> | |
| <head> | |
| <title>PHP Calculator Example: Version 2</title> | |
| </head> | |
| <body> | |
| <h3>PHP Calculator (Version 2)</h3> | |
| <form method="get" action="<?php echo $_SERVER['PHP_SELF']; ?>"> | |
| x = <input type="text" name="x" size="5" value="<?php print $x; ?>"/> | |
| op = | |
| <select name="op"> | |
| <option value="+" <?php if ($op=='+') echo 'selected="selected"';?>>+</option> | |
| <option value="-" <?php if ($op=='-') echo 'selected="selected"';?>>-</option> | |
| <option value="*" <?php if ($op=='*') echo 'selected="selected"';?>>*</option> | |
| <option value="/" <?php if ($op=='/') echo 'selected="selected"';?>>/</option> | |
| </select> | |
| y = <input type="text" name="y" size="5" value="<?php print $y; ?>"/> | |
| <input type="submit" name="calc" value="Calculate"/> | |
| </form> | |
| <?php | |
| if(isset($calc)) { | |
| // check that $x & $y are numeric | |
| if (is_numeric($x) && is_numeric($y)) { | |
| // call the caculate function and pass $x, $y & $op as args. | |
| $prod = calculate($x, $y, $op); | |
| // print the result | |
| echo "<p>$x $op $y = $prod</p>"; | |
| } | |
| else { | |
| // unaccepatable values | |
| echo "<p>x and y values are required to be numeric ... | |
| please re-enter values</p>"; | |
| } | |
| } | |
| ?> | |
| <hr height="2px" align="left" width="340px" /> | |
| <p>See code: <a href="calculator_v2.phps">calculator_v2.phps</a></p> | |
| <p>Notes:<br/> | |
| i) codes a drop down selection box to list operations<br/> | |
| ii) makes use of the select (case) statement.<br/> | |
| iii) traps non-numeric entires<br/> | |
| iv) catches devide by zero error<p> | |
| </body> | |
| </html> |
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