Undefined variable php как исправить

undefined variable или как исправить ошибку «undefined variable» -я даже и забыл, что такой вид ошибки существует!

Подробно об ошибке «undefined variable«

1. undefined variable
2. Как выключить ошибку undefined variable

Notice undefined variable

Что означает «Notice undefined variable» — начнем с перевода… Когда вы встречаете разного рода ошибки — просто переведите данную ошибку — потому, что ошибка она на то и ошибка, что в смысле этой ошибки и есть ответ.


Notice — переводится как :

уведомление, внимание, объявление, нотис сущ
замечать, уведомлять, обращать внимание гл

undefined — переводится как :

неопределенный прил

variable — переводится как :

переменная сущ
изменчивый прил
регулируемый, изменяющийся прич

Итого, если суммировать и перевести с русского на русский:

«Notice undefined variable» — внимание! Неопределенная переменная…


Т.е. вы выводите переменную, которая не существует! Вообще — это очень неудобная ошибка, я её просто выключил!

Пример возникновения «undefined variable»

Самый простой пример… возникновения ошибки «undefined variable«. Переменная ранее не была создана и выводим таким образом с помощью echo:

echo $example_var;

Для предотвращения такого рода ошибки, выше echo нужно создать данную переменную:

$example_var = »;

echo $example_var;

Как выключить ошибку undefined variable

Почему я написал выше, что я забыл, что вообще существует такой вид ошибки, как «» — да просто потому, что я каждый день не покупаю новый хостинг, а нахожусь уже на одном хостинге ruweb — 10 лет

И у меня с самого начала, данная ошибка была отключена.

Но если у вас не так.
Стоит ли отключать вывод ошибки undefined variable.

По этому поводу — всегда будут два мнения за и против.

Я отключаю, потому, что мне не нужна именно эта ошибка.

Смотри как отключить ошибки, или как показывать ошибки, только админу.

Можете не благодарить, лучше помогите!

COMMENTS+

 
BBcode

  John Mwaniki /   10 Dec 2021

This error, as it suggests, occurs when you try to use a variable that has not been defined in PHP.

Example 1

<?php
echo $name;
?>

Output

Notice: Undefined variable: name in /path/to/file/file.php on line 2.

Example 2

<?php
$num1 = 27;
$answer = $num1 + $num2;
echo $answer;
?>

Output

Notice: Undefined variable: num2 in /path/to/file/file.php on line 3.

In our above two examples, we have used a total of 4 variables which include $name, $num1, $num2, and $answer.

But out of all, only two ($name and $num2) have resulted in the «undefined variable» error. This is because we are trying to use them before defining them (ie. assigning values to them).

In example 1, we are trying to print/display the value of the variable $name, but we had not yet assigned any value to it.

In example 2, we are trying to add the value of $num1 to the value of $num2 and assign their sum to $answer. However, we have not set any value for $num2.

To check whether a variable has been set (ie. assigned a value), we use the in-built isset() PHP function.

Syntax

isset($variable)

We pass the variable name as the only argument to the function, where it returns true if the variable has been set, or false if the variable has not been set.

Example

<?php
//Example 1
$name = "Raju Rastogi";
if(isset($name)){
  $result = "The name is $name";
}
else{
  $result = "The name has not been set";
}
echo $result;
//Output: The name is Raju Rastogi
echo "<br>"


//Example 2
if(isset($profession)){
  $result = "My profession is $profession";
}
else{
  $result = "The profession has not been set";
}
echo $result;
//Output: The profession has not been set
?>

In our first example above, we have defined a variable ($name) by creating it and assigning it a value (Raju Rastogi) and thus the isset() function returns true.

In our second example, we had not defined our variable ($profession) before passing to the isset() function and thus the response is false.

The Fix for Undefined variable error

Here are some ways in which you can get rid of this error in your PHP program.

1. Define your variables before using them

Since the error originates from using a variable that you have not defined (assigned a value to), the best solution is to assign a value to the variable before using it anywhere in your program.

For instance, in our first example, the solution is to assign a value to the variable $name before printing it.

<?php
$name = "Farhan Qureshi";
echo $name;
//Output: Farhan Qureshi
?>

The above code works without any error.

2. Validating variables with isset() function

Another way to go about this is to validate whether the variables have been set before using them.

<?php
$num1 = 27;
if(isset($num1) && isset($num2)){
$answer = $num1 + $num2;
echo $answer;
}
?>

The addition operation will not take place because one of the required variables ($num2) has not been set.

<?php
$num1 = 27;
$num2 = 8;
if(isset($num1) && isset($num2)){
$answer = $num1 + $num2;
echo $answer;
}
//Oputput: 35
?>

The addition this time will take place because the two variables required have been set.

3. Setting the undefined variable to a default value

You can also check whether the variables have been defined using the isset() function and if not, assign them a default value.

For instance, you can set a blank «» value for variables expected to hold a string value, and a 0 for those values expect to hold a numeric value.

Example

<?php
$name = "John Doe";
$name = isset($name) ? $name : '';
$age= isset($age) ? $age: 0;
echo "My name is $name and I am $age yrs old.";
//Output: My name is John Doe and I am 0 yrs old.
?>

4. Disabling Notice error reporting

This is always a good practice to hide errors from the website visitor. In case these errors are visible on the website to the web viewers, then this solution will be very useful in hiding these errors.

This option does not prevent the error from happening, it just hides it.

Open the php.ini file in a text editor, and find the line below:

error_reporting = E_ALL

Replace it with:

error_reporting = E_ALL & ~E_NOTICE

Now the ‘NOTICE’ type of errors won’t be shown again. However, the other types of errors will be shown.

Another way of disabling these errors is to add the line of code below on the top of your PHP code.

error_reporting (E_ALL ^ E_NOTICE);

That’s all for this article. It’s my hope that it has helped you solve the error.

[Solved]: Notice: Undefined variable in PHP

This error, as it suggests, occurs when you try to use a variable that has not been defined in PHP.

Example 1

Notice: Undefined variable: name in /path/to/file/file.php on line 2.

Example 2

Notice: Undefined variable: num2 in /path/to/file/file.php on line 3.

In our above two examples, we have used a total of 4 variables which include $name , $num1 , $num2 , and $answer .

But out of all, only two ($name and $num2) have resulted in the «undefined variable» error. This is because we are trying to use them before defining them (ie. assigning values to them).

In example 1, we are trying to print/display the value of the variable $name, but we had not yet assigned any value to it.

In example 2, we are trying to add the value of $num1 to the value of $num2 and assign their sum to $answer. However, we have not set any value for $num2.

To check whether a variable has been set (ie. assigned a value), we use the in-built isset() PHP function.

Syntax

We pass the variable name as the only argument to the function, where it returns true if the variable has been set, or false if the variable has not been set.

Example

In our first example above, we have defined a variable ($name) by creating it and assigning it a value (Raju Rastogi) and thus the isset() function returns true.

In our second example, we had not defined our variable ($profession) before passing to the isset() function and thus the response is false.

The Fix for Undefined variable error

Here are some ways in which you can get rid of this error in your PHP program.

1. Define your variables before using them

Since the error originates from using a variable that you have not defined (assigned a value to), the best solution is to assign a value to the variable before using it anywhere in your program.

For instance, in our first example, the solution is to assign a value to the variable $name before printing it.

The above code works without any error.

2. Validating variables with isset() function

Another way to go about this is to validate whether the variables have been set before using them.

The addition operation will not take place because one of the required variables ($num2) has not been set.

The addition this time will take place because the two variables required have been set.

3. Setting the undefined variable to a default value

You can also check whether the variables have been defined using the isset() function and if not, assign them a default value.

For instance, you can set a blank «» value for variables expected to hold a string value, and a for those values expect to hold a numeric value.

Example

4. Disabling Notice error reporting

This is always a good practice to hide errors from the website visitor. In case these errors are visible on the website to the web viewers, then this solution will be very useful in hiding these errors.

This option does not prevent the error from happening, it just hides it.

Open the php.ini file in a text editor, and find the line below:

Replace it with:

Now the ‘NOTICE’ type of errors won’t be shown again. However, the other types of errors will be shown.

Another way of disabling these errors is to add the line of code below on the top of your PHP code.

error_reporting (E_ALL ^ E_NOTICE);

That’s all for this article. It’s my hope that it has helped you solve the error.

Источник

Notice: Undefined Variable in PHP

Notice: Undefined variable

This error means that within your code, there is a variable or constant which is not set. But you may be trying to use that variable.

The error can be avoided by using the isset() function.This function will check whether the variable is set or not.

Error Example:

Output:

In the above example, we are displaying value stored in the ‘name’ and ‘age’ variable, but we didn’t set the ‘age’ variable.

Here are two ways to deal with such notices.

1. Resolve such notices.
2. Ignore such notices.

Fix Notice: Undefined Variable by using isset() Function

This notice occurs when you use any variable in your PHP code, which is not set.

Solutions:

To fix this type of error, you can define the variable as global and use the isset() function to check if the variable is set or not.

Example:

Set Index as blank

Ignore PHP Notice: Undefined variable

You can ignore this notice by disabling reporting of notice with option error_reporting.

1. Disable Display Notice in php.ini file

Open php.ini file in your favorite editor and search for text “error_reporting” the default value is E_ALL. You can change it to E_ALL &

Notice: Undefined variable

This error means that within your code, there is a variable or constant which is not set. But you may be trying to use that variable.

The error can be avoided by using the isset() function.This function will check whether the variable is set or not.

Error Example:

<?php
$name='Stechies';
echo $name;
echo $age;
?>

Output:

STechies
Notice: Undefined variable: age in testsite.locvaraible.php on line 4

In the above example, we are displaying value stored in the ‘name’ and ‘age’ variable, but we didn’t set the ‘age’ variable.

Here are two ways to deal with such notices.

1. Resolve such notices.
2. Ignore such notices.

Fix Notice: Undefined Variable by using isset() Function

This notice occurs when you use any variable in your PHP code, which is not set.

Solutions:

To fix this type of error, you can define the variable as global and use the isset() function to check if the variable is set or not.

Example:

<?php
global $name;
global $age;
$name = 'Stechies';

if(!isset($name)){
$name = 'Variable name is not set';
}
if(!isset($age)){
$age = 'Varaible age is not set';
}
echo 'Name: ' . $name.'<br>';
echo 'Age: ' . $age;
?>

Set Index as blank

<?php
$name = 'Stechies';

// Set Variable as Blank
$name = isset($name) ? $name : '';
$age= isset($age) ? $age: '';

echo 'Name: ' . $name.'<br>';
echo 'Age: ' . $age;
?>

Ignore PHP Notice: Undefined variable

You can ignore this notice by disabling reporting of notice with option error_reporting.

1. Disable Display Notice in php.ini file

Open php.ini file in your favorite editor and search for text “error_reporting” the default value is E_ALL. You can change it to E_ALL & ~E_NOTICE.

By default:

error_reporting = E_ALL

Change it to:

error_reporting = E_ALL & ~E_NOTICE

Now your PHP compiler will show all errors except ‘Notice.’

2. Disable Display Notice in PHP Code

If you don’t have access to make changes in the php.ini file, In this case, you need to disable the notice by adding the following code on the top of your PHP page.

<?php error_reporting (E_ALL ^ E_NOTICE); ?>

Now your PHP compiler will show all errors except ‘Notice.’

Главное правило: переменная должна быть объявлена до её использования. Если сделать это позже, то программа просто не заработает.

<?php

print_r($greeting);
$greeting = 'Father!';

Запуск программы выше завершается с ошибкой PHP Notice: Undefined variable: greeting. Undefined variable — это ошибка обращения. Она означает, что в коде используется имя (говорят идентификатор), который не определен. Причём в самой ошибке явно указан индентификатор переменой: greeting. Кроме неправильного порядка определения, в PHP встречаются банальные опечатки — как при использовании переменной, так и во время её объявления.

Количество подобных ошибок уменьшается за счёт использования правильно настроенного редактора. Такой редактор подсвечивает имена, которые используются без объявления, и предупреждает о возможных проблемах.

Задание

Найдите в программе необъявленную переменную и объявите её, присвоив ей значение 'Dragon'.

После выполнения программы результат на экране должен выглядеть так:

Targaryen and Dragon

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