isset submit in php with code examples

The isset() function in PHP is used to check if a variable has been set and is not null. It returns a boolean value, either true or false.

Here is an example of how to use isset() to check if a form has been submitted:

<?php
if (isset($_POST['submit'])) {
  // form has been submitted, do something
  echo "Form has been submitted";
} else {
  // form has not been submitted, display the form
  echo '<form method="post">';
  echo '<input type="submit" name="submit" value="Submit">';
  echo '</form>';
}
?>

In this example, we are using the $_POST superglobal array to check if the form has been submitted. The $_POST array contains data submitted through a form using the POST method. The name attribute of the input element is set to submit, which is what we are checking for in the isset() function.

If the form has been submitted, the code inside the first if statement will execute, and the text "Form has been submitted" will be displayed. If the form has not been submitted, the code inside the else statement will execute, and the form will be displayed.

It's also worth noting that, empty() function also could be used in place of isset() function, but it is not recommended because empty() check if a variable is empty, null, false or 0, but isset() only check if a variable is set and not null.

<?php
if (!empty($_POST['submit'])) {
  // form has been submitted, do something
  echo "Form has been submitted";
} else {
  // form has not been submitted, display the form
  echo '<form method="post">';
  echo '<input type="submit" name="submit" value="Submit">';
  echo '</form>';
}
?>

In this example, we are using the empty() function to check if the form has been submitted, and it's not empty. This will return false if the submit button has been pressed, and true if the form has not been submitted.

In conclusion, isset() is a useful function in PHP for checking if a form has been submitted, and it allows you to take appropriate action based on whether the form has been submitted or not. It is always recommended to use isset() over empty() for this purpose.

Another way to check if a form has been submitted in PHP is to use the $_SERVER['REQUEST_METHOD'] superglobal variable. This variable contains the request method used to access the current script, such as GET, POST, PUT, etc.

<?php
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
  // form has been submitted, do something
  echo "Form has been submitted";
} else {
  // form has not been submitted, display the form
  echo '<form method="post">';
  echo '<input type="submit" name="submit" value="Submit">';
  echo '</form>';
}
?>

In this example, we are checking if the $_SERVER['REQUEST_METHOD'] is equal to 'POST'. If it is, the form has been submitted, and the code inside the first if statement will execute. If not, the form has not been submitted, and the code inside the else statement will execute.

Another way to check if a form has been submitted is to use the array_key_exists() function. This function checks if a specified key exists in an array.

<?php
if (array_key_exists('submit', $_POST)) {
  // form has been submitted, do something
  echo "Form has been submitted";
} else {
  // form has not been submitted, display the form
  echo '<form method="post">';
  echo '<input type="submit" name="submit" value="Submit">';
  echo '</form>';
}
?>

In this example, we are using the array_key_exists() function to check if the 'submit' key exists in the $_POST array. If it does, the form has been submitted, and the code inside the first if statement will execute. If not, the form has not been submitted, and the code inside the else statement will execute.

It's worth noting that, in addition to form submission, there are other use cases for the isset() function in PHP. For example, you can use it to check if a variable has been set before using it in a script, or to check if a session variable has been set before attempting to access its value.

In addition, isset() can also be used to check if an element of an array has been set. For example, if you have an array called $myArray and you want to check if the element at index 5 has been set, you can use the following code:

if(isset($myArray[5])){
  //do something
}

In conclusion, there are several ways to check if a form has been submitted in PHP, including using the isset(), $_SERVER['REQUEST_METHOD'], empty(), array_key_exists() functions, and each one has its own use case and implementation. It's important to choose the appropriate method for your specific situation, depending on your requirements and the data you are working with.

Popular questions

1. What is the purpose of the isset() function in PHP?

• The isset() function in PHP is used to check if a variable has been set and is not null. It returns a boolean value, either true or false.

2. How can we check if a form has been submitted in PHP using the isset() function?

• We can use the isset() function to check if a form has been submitted by using the $_POST superglobal array. For example:

if (isset($_POST['submit'])) {
  // form has been submitted, do something
  echo "Form has been submitted";
} else {
  // form has not been submitted, display the form
  echo '<form method="post">';
  echo '<input type="submit" name="submit" value="Submit">';
  echo '</form>';
}

3. What is the difference between isset() and empty() function?

• empty() function also could be used in place of isset() function, but it is not recommended because empty() check if a variable is empty, null, false or 0, but isset() only check if a variable is set and not null.

4. Can isset() function be used to check if an element of an array has been set?

• Yes, isset() can also be used to check if an element of an array has been set. For example, if you have an array called $myArray and you want to check if the element at index 5 has been set, you can use the following code:

if(isset($myArray[5])){
  //do something
}

5. Are there any other ways to check if a form has been submitted in PHP?

• Yes, there are several ways to check if a form has been submitted in PHP, including using the $_SERVER['REQUEST_METHOD'], empty(), array_key_exists() functions. Each one has its own use case and implementation. It's important to choose the appropriate method for your specific situation, depending on your requirements and the data you are working with.

Tag

Validation.