'Submit form to calculate quadratic equation

Am just learning html. I need to write code that solves the quadratic equation formula. I tried php code embeding in html but am getting blank output. How do I get user values a, b, c and display conditional answers?

htmlformulaquadratic


Solution 1:[1]

Here's a simple example of what you need to do. First make a HTML form:

<form method="post" action="index.php">
    <input type="text" name="a" value="Enter 'a'" />
    <input type="text" name="b" value="Enter 'b'" />
    <input type="text" name="c" value="Enter 'c'" />
    <input type="submit" name='calc' value="Calculate" />
</form>

There is your form. Now the calculations:

<?php
    // Check if the form is submitted 
    if (isset($_POST['calc'])) {
        //assign variables
        $a = $_POST['a'];
        $b = $_POST['b'];
        $c = $_POST['c'];

        //after assigning variables you can calculate your equation
        $d = $b * $b - (4 * $a * $c);
        $x1 = (-$b + sqrt($d)) / (2 * $a);
        $x2 = (-$b - sqrt($d)) / (2 * $a);
        echo "x<sub>1</sub> = {$x1} and x<sub>2</sub> = {$x2}";
    } else {
        // here you can put your HTML form
    }
?>

You need to do more checks on it, but as I said before this is a simple example.

Solution 2:[2]

Edit: learn from the source , the official php site: http://php.net/manual/en/tutorial.forms.php

1.Create a form with the fields you want. <form method='post' ....>...</form>

2.The user submit the form and then write a PHP code which get the posted data ($_POST) and manipulate it according to the quadratic equation formula.

3.Echo the result.

Solution 3:[3]

I have smaller example.

This file sends data from form to itself. When it sends something - result of condition 

$_SERVER['REQUEST_METHOD']=='POST'

is true. If its true - server process code in "if" block. It assigns data sent from form to 2 variables, then adds them and store in "$sum" variable. Result is displayed.

<html>
    <body>    
        <form method="POST">

            <p>
            A: <br />
                <input name="number_a" type="text"></input>
            </p>

            <p>B: <br />
                <input name="number_b" type="text"></input>
            </p>

            <p>
                <input type="submit"/>
            </p>

        </form>

<?php


    if ($_SERVER['REQUEST_METHOD']=='POST') // process "if block", if form was sumbmitted
    {
        $a = $_POST['number_a'] ; // get first number form data sent by form to that file itself
        $b = $_POST['number_b'] ; // get second number form data sent by form to that file itself

        $sum = $a + $b;  // calculate something

    echo "A+B=" . $sum; // print this to html source, use "." (dot) for append text to another text/variable
    }

?>

    </body>
</html>

You need PHP server to test/use this! PHP file must be processed by web server, which creates page. Opening php file from disk will not work. If you need more explanations - ask for it in comments.

Sources

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Source: Stack Overflow

Solution Source
Solution 1
Solution 2
Solution 3

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