问题
I'm creating a basic PHP calculator that lets you enter two values and chose your operator then displays the answer. Everything is working fine except it's not outputting the answer to the browser.
Here are the codes for my html and PHP files:
<head>
<meta charset="utf-8">
<title>Calculator</title>
</head>
<body>
<form method="post" attribute="post" action="disp_form.php">
<p>First Value:<br/>
<input type="text" id="first" name="first"></p>
<p>Second Value:<br/>
<input type="text" id="second" name="second"></p>
<input type="radio" name="group1" id="add" value="add" checked="true"><p>+</p><br/>
<input type="radio" name="group1" id="subtract" value="subtract"><p>-</p><br/>
<input type="radio" name="group1" id="times" value="times"><p>x</p><br/>
<input type="radio" name="group1" id="divide" value="divide"><p>/</p><br/>
<p></p>
<button type="submit" name="answer" id="answer" value="answer">Calculate</button>
</form>
</body>
</html>
PHP file:
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Answer</title>
</head>
<body>
<p>The answer is:
<?php
if($_POST['group1'] == add) {
echo "$first + $second";
}
else if($_POST['group1'] == subtract) {
echo "$first - $second";
}
else if($_POST['group1'] == times) {
echo "$first * $second";
}
else($_POST['group1'] == divide) {
echo "$first / $second";
}
?>
</p>
</body>
</html>
回答1:
<?php
$result = "";
class calculator
{
var $a;
var $b;
function checkopration($oprator)
{
switch($oprator)
{
case '+':
return $this->a + $this->b;
break;
case '-':
return $this->a - $this->b;
break;
case '*':
return $this->a * $this->b;
break;
case '/':
return $this->a / $this->b;
break;
default:
return "Sorry No command found";
}
}
function getresult($a, $b, $c)
{
$this->a = $a;
$this->b = $b;
return $this->checkopration($c);
}
}
$cal = new calculator();
if(isset($_POST['submit']))
{
$result = $cal->getresult($_POST['n1'],$_POST['n2'],$_POST['op']);
}
?>
<form method="post">
<table align="center">
<tr>
<td><strong><?php echo $result; ?><strong></td>
</tr>
<tr>
<td>Enter 1st Number</td>
<td><input type="text" name="n1"></td>
</tr>
<tr>
<td>Enter 2nd Number</td>
<td><input type="text" name="n2"></td>
</tr>
<tr>
<td>Select Oprator</td>
<td><select name="op">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select></td>
</tr>
<tr>
<td></td>
<td><input type="submit" name="submit" value=" = "></td>
</tr>
</table>
</form>
回答2:
Personally I would do a switch instead of all this if, else if, else
$first = $_POST['first'] + 0;//a small "hack" to make sure its an int but allow negs!!
$second= $_POST['second'] + 0;
$operator = $_POST["group1"];
switch($operator)
{
case "add"
echo "Answer is: " .$first + $second;
break;
case "subtract"
echo "Answer is: " .$first - $second;
break;
case "times"
echo "Answer is: " .$first * $second;
break;
case "divide"
echo "Answer is: " .$first / $second;
break;
}
回答3:
You need to assign $first and $second
$first = $_POST['first'];
$second= $_POST['second'];
Also, As Travesty3 said, you need to do your arithmetic outside of the quotes:
echo $first + $second;
回答4:
You also need to put the [== 'add'] math operation into quotes
if($_POST['group1'] == 'add') {
echo $first + $second;
}
complete code schould look like that :
<?php
$first = $_POST['first'];
$second= $_POST['second'];
if($_POST['group1'] == 'add') {
echo $first + $second;
}
else if($_POST['group1'] == 'subtract') {
echo $first - $second;
}
else if($_POST['group1'] == 'times') {
echo $first * $second;
}
else if($_POST['group1'] == 'divide') {
echo $first / $second;
}
?>
回答5:
You need to get the values the same way to get the calculator operation which looks like:
<?php
if($_POST['group1'] == add) {
echo "$_POST['first']+ $_POST['second'];
}
... and so on
?>
Or, to make it easier, just do:
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Answer</title>
</head>
<body>
<p>The answer is:
<?php
$first = $_POST['first'];
$second= $_POST['second'];
if($_POST['group1'] == add) {
echo "$first + $second";
}
else if($_POST['group1'] == subtract) {
echo "$first - $second";
}
else if($_POST['group1'] == times) {
echo "$first * $second";
}
else($_POST['group1'] == divide) {
echo "$first / $second";
}
?>
</p>
</body>
</html>
回答6:
$first = doubleval($_POST['first']);
$second = doubleval($_POST['second']);
if($_POST['group1'] == 'add') {
echo "$first + $second = ".($first + $second);
}
// etc
回答7:
Check string using single quotes
Ex. $_POST['group1'] == 'add'
回答8:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Calculator</title>
</head>
<body>
HTML Code is here:
<form method="post">
<input type="text" name="numb1">
<input type="text" name="numb2">
<select name="operator" id="">
<option>None</option>
<option>Add</option>
<option>Subtract</option>
<option>Multiply</option>
<option>Divide</option>
<option>Square</option>
</select>
<button type="submit" name="submit" value="submit">Calculate</button>
</form>
PHP Code:
<?php
if (isset($_POST['submit'])) {
$result1 = $_POST['numb1'];
$result2 = $_POST['numb2'];
$operator = $_POST['operator'];
switch ($operator) {
case 'None':
echo "You need to select any operator";
break;
case 'Add':
echo $result1 + $result2;
break;
case 'Subtract':
echo $result1 - $result2;
break;
case 'Multiply':
echo $result1 * $result2;
break;
case 'Divide':
echo $result1 / $result2;
break;
case 'Square':
echo $result1 ** $result2;
break;
}
}
?>
enter code here
</body>
</html>
回答9:
Make this changes in php file
<html>
<head>
<meta charset="utf-8">
<title>Answer</title>
</head>
<body>
<p>The answer is:
<?php
$first = $_POST['first'];
$second= $_POST['second'];
if($_POST['group1'] == 'add') {
echo $first + $second;
}
else if($_POST['group1'] == 'subtract') {
echo $first - $second;
}
else if($_POST['group1'] == 'times') {
echo $first * $second;
}
else if($_POST['group1'] == 'divide') {
echo $first / $second;
}
else {
echo "Enter the numbers properly";
}
?>
</p>
</body>
</html>
来源：https://stackoverflow.com/questions/21445245/simple-php-calculator