CODEWITHSUNDEEP
phphtmlformsinput
user7894560
user7894560

Reputation:

any way to prevent an echo printing out before its needed to do so?

i have a multiplication table which works perfectly, save for one tiny mishap. i need the message "invalid entry!" to ONLY appear when i submit an empty query via my input field. the problem lies in the message being there, staring me in the face upon first opening the table form in my localhost.

any ideas? thanks in advance.

the code:

<html>

<form method="post" action="php32-table.php">
  <input type="text" name="num">
  <input type="submit" value="get table">
</form>

</html>

<?php

$num = isset($_POST["num"]) ? $_POST["num"] : "";
  if($num) {
  for($i = 1; $i <= 10; $i++)
  {
  $mul = $num * $i;
  echo "$num * $i = $mul<br>";
  }
  } else {
  echo "invalid entry!";
  }
?>

Upvotes: 0

Views: 58

Answers (5)

nonybrighto
nonybrighto

Reputation: 9581

Num will always be set since it is a textfield. What you need to do is check if the field is empty. The code below should work.

<?php
  if (isset($_POST["submit"])){
    if(!empty(trim($_POST['num'])) {
       $num = $_POST['num'];
       for($i = 1; $i <= 10; $i++)
       {
          $mul = $num * $i;  
          echo "$num * $i = $mul<br>";
       }
    } else {
         echo "invalid entry!";
    }
  }
?>

Upvotes: 1

user5633496
user5633496

Reputation:

You have to check the $_POST['submit'] is set or not

<html>

<form method="post" action="php32-table.php">
  <input type="text" name="num">
  <input type="submit" name='submit' value="get table">
</form> 

</html>

<?php

if (isset($_POST["submit"])){

$num = isset($_POST["num"]) ? $_POST["num"] : "";


  if($num) {
  for($i = 1; $i <= 10; $i++)
  {
  $mul = $num * $i;
  echo "$num * $i = $mul<br>";
  }
  } else {
  echo "invalid entry!";
  }
}
?>

Upvotes: 0

Vimukthi Guruge
Vimukthi Guruge

Reputation: 285

change your input type to number. 

<input type="number" name="num">

Here the PHP code 

if(isset($_POST["num"])){

$num = $_POST["num"];


  if($num)
  {
      for($i = 1; $i <= 10; $i++)
      {
        $mul = $num * $i;
        echo "$num * $i = $mul<br>";
      }
  }
  else
  {
    echo "invalid entry!";
  }

}

?>

Upvotes: 0

Option
Option

Reputation: 2645

I removed the link to action for testing purposes, I also prefer personally to run the PHP for the form within the same file, so my example below is exactly how to do that. You can always refer to your original and place the php within the php32-table.php file.

You can run this from the submission side by adding in name="submit" like below:

<form method="post" action="">
    <input type="text" name="num">
    <input type="submit" value="get table" name="submit">
</form>

You can then check if the submit button has been pressed by using isset and if it has been clicked then run the code between { } like below:

<?php
if (isset($_POST['submit']))
{
    $num = isset($_POST["num"]) ? $_POST["num"] : "";
    if ($num) {
        for ($i = 1; $i <= 10; $i++)
        {
            $mul = $num * $i;
            echo "$num * $i = $mul<br>";
        }
    } else {
        echo "invalid entry!";
    }
}
?>

to be honest, to keep it cleaner i'd remove: $num = isset($_POST["num"]) ? $_POST["num"] : ""; and simply change that line to: 

if (!empty($_POST['num']))
{
    // run code 
} else {
    // output error
}

Upvotes: 0

Jerodev
Jerodev

Reputation: 33186

You could check if the $_POST["num"] variable is set. This way you can know if the form has been posted.

<?php
  if (isset($_POST["num"]))
  {
    $num = isset($_POST["num"]) ? $_POST["num"] : "";
    if ($num) {
      for ($i = 1; $i <= 10; $i++)
      {
        $mul = $num * $i;
        echo "$num * $i = $mul<br>";
      }
    } else {
      echo "invalid entry!";
    }
  }
?>

Upvotes: 0

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