How to implement a simple calculator function through PHP

How to implement a simple calculator function through PHP

The calculator is a common application that can perform basic mathematical operations. In this article, we will learn how to write a simple calculator using PHP to perform addition, subtraction, multiplication and division operations.

First, we need to create an HTML form for users to enter values ​​and select operators. The code is as follows:

<form method="post">
  <input type="text" name="num1" placeholder="请输入第一个数字" required>
  <select name="operator">
    <option value="+">+</option>
    <option value="-">-</option>
    <option value="*">*</option>
    <option value="/">/</option>
  </select>
  <input type="text" name="num2" placeholder="请输入第二个数字" required>
  <button type="submit">计算</button>
</form>

In the above code, we created two input boxes for users to enter values, a drop-down menu for selecting operators, and a submit button. The form's submission method is set to POST.

Next, we need to process the form data and perform corresponding calculation operations. In PHP code, we can use conditional statements to perform different calculation operations based on the operator selected by the user. The code is as follows:

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
  $num1 = $_POST['num1'];
  $num2 = $_POST['num2'];
  $operator = $_POST['operator'];

  if (!is_numeric($num1) || !is_numeric($num2)) {
    echo "请输入有效数字！";
  } else {
    switch ($operator) {
      case '+':
        $result = $num1 + $num2;
        break;
      case '-':
        $result = $num1 - $num2;
        break;
      case '*':
        $result = $num1 * $num2;
        break;
      case '/':
        if ($num2 == 0) {
          echo "除数不能为0！";
        } else {
          $result = $num1 / $num2;
        }
        break;
      default:
        echo "请选择有效运算符！";
    }

    echo "计算结果：$result";
  }
}

In the above code, we first obtain the values ​​and operators entered by the user through the $_POST array. Then, we use the is_numeric function to check whether the entered numerical value is a valid number. If it is not a number, an error message is output.

Next, we use the switch statement to perform the corresponding calculation operation based on the operator selected by the user, and store the result in the $result variable. If the division operator is selected, we also need to check whether the divisor is 0 to avoid the error of dividing by 0.

Finally, we use the echo statement to output the calculation results.

Now, we can perform calculations by opening this PHP file in a browser and entering values ​​and selecting operators. The calculation results will be displayed on the page.

Summary:
Through the above steps, we successfully wrote a simple calculator function using PHP. Users can enter numerical values ​​and select operators, then perform calculations by clicking the Calculate button and get the output of the calculated results. This simple calculator can be used as an exercise project for learning the basics of PHP, and can also be used for some simple mathematical calculation needs.

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