How to make a calculator in php

Make a calculator in PHP with an example—learn how to use basic math functions to build a calculator in PHP.

Creating a Calculator in PHP

Creating a basic calculator in PHP is relatively easy, and requires the following steps:

Step 1: Create the HTML and PHP

The first step is to create the HTML form with the necessary inputs. This form should have two text fields, a dropdown menu for the operator, and a submit button. This HTML form can then be combined with PHP code to perform the calculation. Here is a basic example of the HTML and PHP:

<form action="calculator.php" method="post">
    <input type="text" name="num1">
    <select name="operator">
        <option value="+">+</option>
        <option value="-">-</option>
        <option value="*">*</option>
        <option value="/">/</option>
    </select>
    <input type="text" name="num2">
    <input type="submit">
</form>

<?php
    $num1 = $_POST['num1'];
    $num2 = $_POST['num2'];
    $operator = $_POST['operator'];

    if ($operator == "+") {
        $result = $num1 + $num2;
    } elseif ($operator == "-") {
        $result = $num1 - $num2;
    } elseif ($operator == "*") {
        $result = $num1 * $num2;
    } elseif ($operator == "/") {
        $result = $num1 / $num2;
    }
?>

This HTML and PHP code will create a basic calculator form. The form will take two numbers as inputs, and an operator to perform the calculation. The PHP code will then take the values from the form and perform the calculation.

Step 2: Display the Result

The next step is to display the result of the calculation. This can be done by simply echoing the result variable:

echo $result;

This will output the result of the calculation on the page. If the calculation was successful, the result will be displayed. If the calculation was unsuccessful, an error message will be displayed.

Step 3: Add Validation

The last step is to add validation to the calculator. This will ensure that only valid inputs are accepted. This can be done by using PHP's built-in functions to check the inputs:

if (is_numeric($num1) && is_numeric($num2)) {
    // perform calculation
} else {
    echo "Error: Please enter valid numbers.";
}

This code will check if the inputs are numeric. If they are, the calculation will be performed. If not, an error message will be displayed. This will ensure that only valid inputs are accepted.

That's it! You now have a basic calculator in PHP. You can further improve the calculator by adding more operators and other features.