The PHP date() function is used to format a time or a date.
--------------------------------------------------------------------------------
The PHP Date() Function
The PHP date() function formats a timestamp to a more readable date and time.
Syntax
date(format,timestamp)
Parameter Description
format Required. Specifies the format of the timestamp
timestamp Optional. Specifies a timestamp. Default is the current date and time (as a timestamp)
--------------------------------------------------------------------------------
PHP Date - What is a Timestamp?
A timestamp is the number of seconds since January 1, 1970 at 00:00:00 GMT. This is also known as the Unix Timestamp.
--------------------------------------------------------------------------------
PHP Date - Format the Date
The first parameter in the date() function specifies how to format the date/time. It uses letters to represent date and time formats. Here are some of the letters that can be used:
d - The day of the month (01-31)
m - The current month, as a number (01-12)
Y - The current year in four digits
An overview of all the letters that can be used in the format parameter, can be found in our PHP Date reference.
Other characters, like"/", ".", or "-" can also be inserted between the letters to add additional formatting:
echo date("Y/m/d");
echo "
";
echo date("Y.m.d");
echo "
";
echo date("Y-m-d");
?>
The output of the code above could be something like this:
2006/07/11
2006.07.11
2006-07-11
--------------------------------------------------------------------------------
PHP Date - Adding a Timestamp
The second parameter in the date() function specifies a timestamp. This parameter is optional. If you do not supply a timestamp, the current time will be used.
In our next example we will use the mktime() function to create a timestamp for tomorrow.
The mktime() function returns the Unix timestamp for a specified date.
Syntax
mktime(hour,minute,second,month,day,year,is_dst)
To go one day in the future we simply add one to the day argument of mktime():
$tomorrow = mktime(0,0,0,date("m"),date("d")+1,date("Y"));echo "Tomorrow is ".date("Y/m/d", $tomorrow);
?>
The output of the code above could be something like this:
Tomorrow is 2006/07/12
--------------------------------------------------------------------------------
PHP Date - Reference
For more information about all the PHP date functions, please visit our PHP Date Reference.
Wednesday, January 23, 2008
PHP $_POST
The $_POST variable is used to collect values from a form with method="post".
--------------------------------------------------------------------------------
The $_POST Variable
The $_POST variable is an array of variable names and values sent by the HTTP POST method.
The $_POST variable is used to collect values from a form with method="post". Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
Example
When the user clicks the "Submit" button, the URL will not contain any form data, and will look something like this:
http://www.w3schools.com/welcome.php
The "welcome.php" file can now use the $_POST variable to catch the form data (notice that the names of the form fields will automatically be the ID keys in the $_POST array):
Welcome .
You are years old!
--------------------------------------------------------------------------------
Why use $_POST?
Variables sent with HTTP POST are not shown in the URL
Variables have no length limit
However, because the variables are not displayed in the URL, it is not possible to bookmark the page.
--------------------------------------------------------------------------------
The $_REQUEST Variable
The PHP $_REQUEST variable contains the contents of both $_GET, $_POST, and $_COOKIE.
The PHP $_REQUEST variable can be used to get the result from form data sent with both the GET and POST methods.
Example
Welcome .
You are years old!
--------------------------------------------------------------------------------
The $_POST Variable
The $_POST variable is an array of variable names and values sent by the HTTP POST method.
The $_POST variable is used to collect values from a form with method="post". Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
Example
When the user clicks the "Submit" button, the URL will not contain any form data, and will look something like this:
http://www.w3schools.com/welcome.php
The "welcome.php" file can now use the $_POST variable to catch the form data (notice that the names of the form fields will automatically be the ID keys in the $_POST array):
Welcome .
You are years old!
--------------------------------------------------------------------------------
Why use $_POST?
Variables sent with HTTP POST are not shown in the URL
Variables have no length limit
However, because the variables are not displayed in the URL, it is not possible to bookmark the page.
--------------------------------------------------------------------------------
The $_REQUEST Variable
The PHP $_REQUEST variable contains the contents of both $_GET, $_POST, and $_COOKIE.
The PHP $_REQUEST variable can be used to get the result from form data sent with both the GET and POST methods.
Example
Welcome .
You are years old!
PHP $_GET
The $_GET variable is used to collect values from a form with method="get".
--------------------------------------------------------------------------------
The $_GET Variable
The $_GET variable is an array of variable names and values sent by the HTTP GET method.
The $_GET variable is used to collect values from a form with method="get". Information sent from a form with the GET method is visible to everyone (it will be displayed in the browser's address bar) and it has limits on the amount of information to send (max. 100 characters).
Example
When the user clicks the "Submit" button, the URL sent could look something like this:
http://www.w3schools.com/welcome.php?name=Peter&age=37
The "welcome.php" file can now use the $_GET variable to catch the form data (notice that the names of the form fields will automatically be the ID keys in the $_GET array):
Welcome .
You are years old!
--------------------------------------------------------------------------------
Why use $_GET?
Note: When using the $_GET variable all variable names and values are displayed in the URL. So this method should not be used when sending passwords or other sensitive information! However, because the variables are displayed in the URL, it is possible to bookmark the page. This can be useful in some cases.
Note: The HTTP GET method is not suitable on large variable values; the value cannot exceed 100 characters.
--------------------------------------------------------------------------------
The $_REQUEST Variable
The PHP $_REQUEST variable contains the contents of both $_GET, $_POST, and $_COOKIE.
The PHP $_REQUEST variable can be used to get the result from form data sent with both the GET and POST methods.
Example
Welcome .
You are years old!
--------------------------------------------------------------------------------
The $_GET Variable
The $_GET variable is an array of variable names and values sent by the HTTP GET method.
The $_GET variable is used to collect values from a form with method="get". Information sent from a form with the GET method is visible to everyone (it will be displayed in the browser's address bar) and it has limits on the amount of information to send (max. 100 characters).
Example
When the user clicks the "Submit" button, the URL sent could look something like this:
http://www.w3schools.com/welcome.php?name=Peter&age=37
The "welcome.php" file can now use the $_GET variable to catch the form data (notice that the names of the form fields will automatically be the ID keys in the $_GET array):
Welcome .
You are years old!
--------------------------------------------------------------------------------
Why use $_GET?
Note: When using the $_GET variable all variable names and values are displayed in the URL. So this method should not be used when sending passwords or other sensitive information! However, because the variables are displayed in the URL, it is possible to bookmark the page. This can be useful in some cases.
Note: The HTTP GET method is not suitable on large variable values; the value cannot exceed 100 characters.
--------------------------------------------------------------------------------
The $_REQUEST Variable
The PHP $_REQUEST variable contains the contents of both $_GET, $_POST, and $_COOKIE.
The PHP $_REQUEST variable can be used to get the result from form data sent with both the GET and POST methods.
Example
Welcome .
You are years old!
PHP Forms and User Input
The PHP $_GET and $_POST variables are used to retrieve information from forms, like user input.
--------------------------------------------------------------------------------
PHP Form Handling
The most important thing to notice when dealing with HTML forms and PHP is that any form element in an HTML page will automatically be available to your PHP scripts.
Form example:
The example HTML page above contains two input fields and a submit button. When the user fills in this form and click on the submit button, the form data is sent to the "welcome.php" file.
The "welcome.php" file looks like this:
Welcome .
You are years old.
A sample output of the above script may be:
Welcome John.
You are 28 years old.
The PHP $_GET and $_POST variables will be explained in the next chapters.
--------------------------------------------------------------------------------
Form Validation
User input should be validated whenever possible. Client side validation is faster, and will reduce server load.
However, any site that gets enough traffic to worry about server resources, may also need to worry about site security. You should always use server side validation if the form accesses a database.
A good way to validate a form on the server is to post the form to itself, instead of jumping to a different page. The user will then get the error messages on the same page as the form. This makes it easier to discover the error.
--------------------------------------------------------------------------------
PHP Form Handling
The most important thing to notice when dealing with HTML forms and PHP is that any form element in an HTML page will automatically be available to your PHP scripts.
Form example:
The example HTML page above contains two input fields and a submit button. When the user fills in this form and click on the submit button, the form data is sent to the "welcome.php" file.
The "welcome.php" file looks like this:
Welcome .
You are years old.
A sample output of the above script may be:
Welcome John.
You are 28 years old.
The PHP $_GET and $_POST variables will be explained in the next chapters.
--------------------------------------------------------------------------------
Form Validation
User input should be validated whenever possible. Client side validation is faster, and will reduce server load.
However, any site that gets enough traffic to worry about server resources, may also need to worry about site security. You should always use server side validation if the form accesses a database.
A good way to validate a form on the server is to post the form to itself, instead of jumping to a different page. The user will then get the error messages on the same page as the form. This makes it easier to discover the error.
PHP Functions
The real power of PHP comes from its functions.
In PHP - there are more than 700 built-in functions available.
--------------------------------------------------------------------------------
PHP Functions
In this tutorial we will show you how to create your own functions.
For a reference and examples of the built-in functions, please visit our PHP Reference.
--------------------------------------------------------------------------------
Create a PHP Function
A function is a block of code that can be executed whenever we need it.
Creating PHP functions:
All functions start with the word "function()"
Name the function - It should be possible to understand what the function does by its name. The name can start with a letter or underscore (not a number)
Add a "{" - The function code starts after the opening curly brace
Insert the function code
Add a "}" - The function is finished by a closing curly brace
Example
A simple function that writes my name when it is called:
function writeMyName()
{
echo "Kai Jim Refsnes";
}writeMyName();
?>
--------------------------------------------------------------------------------
Use a PHP Function
Now we will use the function in a PHP script:
function writeMyName()
{
echo "Kai Jim Refsnes";
}echo "Hello world!
";
echo "My name is ";
writeMyName();
echo ".
That's right, ";
writeMyName();
echo " is my name.";
?>
The output of the code above will be:
Hello world!
My name is Kai Jim Refsnes.
That's right, Kai Jim Refsnes is my name.
--------------------------------------------------------------------------------
PHP Functions - Adding parameters
Our first function (writeMyName()) is a very simple function. It only writes a static string.
To add more functionality to a function, we can add parameters. A parameter is just like a variable.
You may have noticed the parentheses after the function name, like: writeMyName(). The parameters are specified inside the parentheses.
Example 1
The following example will write different first names, but the same last name:
function writeMyName($fname)
{
echo $fname . " Refsnes.
";
}echo "My name is ";
writeMyName("Kai Jim");echo "My name is ";
writeMyName("Hege");echo "My name is ";
writeMyName("Stale");
?>
The output of the code above will be:
My name is Kai Jim Refsnes.
My name is Hege Refsnes.
My name is Stale Refsnes.
Example 2
The following function has two parameters:
function writeMyName($fname,$punctuation)
{
echo $fname . " Refsnes" . $punctuation . "
";
}echo "My name is ";
writeMyName("Kai Jim",".");echo "My name is ";
writeMyName("Hege","!");echo "My name is ";
writeMyName("Ståle","...");
?>
The output of the code above will be:
My name is Kai Jim Refsnes.
My name is Hege Refsnes!
My name is Ståle Refsnes...
--------------------------------------------------------------------------------
PHP Functions - Return values
Functions can also be used to return values.
Example
function add($x,$y)
{
$total = $x + $y;
return $total;
}echo "1 + 16 = " . add(1,16);
?>
The output of the code above will be:
1 + 16 = 17
In PHP - there are more than 700 built-in functions available.
--------------------------------------------------------------------------------
PHP Functions
In this tutorial we will show you how to create your own functions.
For a reference and examples of the built-in functions, please visit our PHP Reference.
--------------------------------------------------------------------------------
Create a PHP Function
A function is a block of code that can be executed whenever we need it.
Creating PHP functions:
All functions start with the word "function()"
Name the function - It should be possible to understand what the function does by its name. The name can start with a letter or underscore (not a number)
Add a "{" - The function code starts after the opening curly brace
Insert the function code
Add a "}" - The function is finished by a closing curly brace
Example
A simple function that writes my name when it is called:
function writeMyName()
{
echo "Kai Jim Refsnes";
}writeMyName();
?>
--------------------------------------------------------------------------------
Use a PHP Function
Now we will use the function in a PHP script:
function writeMyName()
{
echo "Kai Jim Refsnes";
}echo "Hello world!
";
echo "My name is ";
writeMyName();
echo ".
That's right, ";
writeMyName();
echo " is my name.";
?>
The output of the code above will be:
Hello world!
My name is Kai Jim Refsnes.
That's right, Kai Jim Refsnes is my name.
--------------------------------------------------------------------------------
PHP Functions - Adding parameters
Our first function (writeMyName()) is a very simple function. It only writes a static string.
To add more functionality to a function, we can add parameters. A parameter is just like a variable.
You may have noticed the parentheses after the function name, like: writeMyName(). The parameters are specified inside the parentheses.
Example 1
The following example will write different first names, but the same last name:
function writeMyName($fname)
{
echo $fname . " Refsnes.
";
}echo "My name is ";
writeMyName("Kai Jim");echo "My name is ";
writeMyName("Hege");echo "My name is ";
writeMyName("Stale");
?>
The output of the code above will be:
My name is Kai Jim Refsnes.
My name is Hege Refsnes.
My name is Stale Refsnes.
Example 2
The following function has two parameters:
function writeMyName($fname,$punctuation)
{
echo $fname . " Refsnes" . $punctuation . "
";
}echo "My name is ";
writeMyName("Kai Jim",".");echo "My name is ";
writeMyName("Hege","!");echo "My name is ";
writeMyName("Ståle","...");
?>
The output of the code above will be:
My name is Kai Jim Refsnes.
My name is Hege Refsnes!
My name is Ståle Refsnes...
--------------------------------------------------------------------------------
PHP Functions - Return values
Functions can also be used to return values.
Example
function add($x,$y)
{
$total = $x + $y;
return $total;
}echo "1 + 16 = " . add(1,16);
?>
The output of the code above will be:
1 + 16 = 17
PHP Looping
Looping statements in PHP are used to execute the same block of code a specified number of times.
--------------------------------------------------------------------------------
Looping
Very often when you write code, you want the same block of code to run a number of times. You can use looping statements in your code to perform this.
In PHP we have the following looping statements:
while - loops through a block of code if and as long as a specified condition is true
do...while - loops through a block of code once, and then repeats the loop as long as a special condition is true
for - loops through a block of code a specified number of times
foreach - loops through a block of code for each element in an array
--------------------------------------------------------------------------------
The while Statement
The while statement will execute a block of code if and as long as a condition is true.
Syntax
while (condition)
code to be executed;
Example
The following example demonstrates a loop that will continue to run as long as the variable i is less than, or equal to 5. i will increase by 1 each time the loop runs:
$i=1;
while($i<=5)
{
echo "The number is " . $i . "
";
$i++;
}
?>
--------------------------------------------------------------------------------
The do...while Statement
The do...while statement will execute a block of code at least once - it then will repeat the loop as long as a condition is true.
Syntax
do
{
code to be executed;
}
while (condition);
Example
The following example will increment the value of i at least once, and it will continue incrementing the variable i as long as it has a value of less than 5:
$i=0;
do
{
$i++;
echo "The number is " . $i . "
";
}
while ($i<5);
?>
--------------------------------------------------------------------------------
The for Statement
The for statement is used when you know how many times you want to execute a statement or a list of statements.
Syntax
for (initialization; condition; increment)
{
code to be executed;
}
Note: The for statement has three parameters. The first parameter initializes variables, the second parameter holds the condition, and the third parameter contains the increments required to implement the loop. If more than one variable is included in the initialization or the increment parameter, they should be separated by commas. The condition must evaluate to true or false.
Example
The following example prints the text "Hello World!" five times:
for ($i=1; $i<=5; $i++)
{
echo "Hello World!
";
}
?>
--------------------------------------------------------------------------------
The foreach Statement
The foreach statement is used to loop through arrays.
For every loop, the value of the current array element is assigned to $value (and the array pointer is moved by one) - so on the next loop, you'll be looking at the next element.
Syntax
foreach (array as value)
{
code to be executed;
}
Example
The following example demonstrates a loop that will print the values of the given array:
$arr=array("one", "two", "three");foreach ($arr as $value)
{
echo "Value: " . $value . "
";
}
?>
--------------------------------------------------------------------------------
Looping
Very often when you write code, you want the same block of code to run a number of times. You can use looping statements in your code to perform this.
In PHP we have the following looping statements:
while - loops through a block of code if and as long as a specified condition is true
do...while - loops through a block of code once, and then repeats the loop as long as a special condition is true
for - loops through a block of code a specified number of times
foreach - loops through a block of code for each element in an array
--------------------------------------------------------------------------------
The while Statement
The while statement will execute a block of code if and as long as a condition is true.
Syntax
while (condition)
code to be executed;
Example
The following example demonstrates a loop that will continue to run as long as the variable i is less than, or equal to 5. i will increase by 1 each time the loop runs:
$i=1;
while($i<=5)
{
echo "The number is " . $i . "
";
$i++;
}
?>
--------------------------------------------------------------------------------
The do...while Statement
The do...while statement will execute a block of code at least once - it then will repeat the loop as long as a condition is true.
Syntax
do
{
code to be executed;
}
while (condition);
Example
The following example will increment the value of i at least once, and it will continue incrementing the variable i as long as it has a value of less than 5:
$i=0;
do
{
$i++;
echo "The number is " . $i . "
";
}
while ($i<5);
?>
--------------------------------------------------------------------------------
The for Statement
The for statement is used when you know how many times you want to execute a statement or a list of statements.
Syntax
for (initialization; condition; increment)
{
code to be executed;
}
Note: The for statement has three parameters. The first parameter initializes variables, the second parameter holds the condition, and the third parameter contains the increments required to implement the loop. If more than one variable is included in the initialization or the increment parameter, they should be separated by commas. The condition must evaluate to true or false.
Example
The following example prints the text "Hello World!" five times:
for ($i=1; $i<=5; $i++)
{
echo "Hello World!
";
}
?>
--------------------------------------------------------------------------------
The foreach Statement
The foreach statement is used to loop through arrays.
For every loop, the value of the current array element is assigned to $value (and the array pointer is moved by one) - so on the next loop, you'll be looking at the next element.
Syntax
foreach (array as value)
{
code to be executed;
}
Example
The following example demonstrates a loop that will print the values of the given array:
$arr=array("one", "two", "three");foreach ($arr as $value)
{
echo "Value: " . $value . "
";
}
?>
PHP Arrays
An array can store one or more values in a single variable name.
--------------------------------------------------------------------------------
What is an array?
When working with PHP, sooner or later, you might want to create many similar variables.
Instead of having many similar variables, you can store the data as elements in an array.
Each element in the array has its own ID so that it can be easily accessed.
There are three different kind of arrays:
Numeric array - An array with a numeric ID key
Associative array - An array where each ID key is associated with a value
Multidimensional array - An array containing one or more arrays
--------------------------------------------------------------------------------
Numeric Arrays
A numeric array stores each element with a numeric ID key.
There are different ways to create a numeric array.
Example 1
In this example the ID key is automatically assigned:
$names = array("Peter","Quagmire","Joe");
Example 2
In this example we assign the ID key manually:
$names[0] = "Peter";
$names[1] = "Quagmire";
$names[2] = "Joe";
The ID keys can be used in a script:
$names[1] = "Quagmire";
$names[2] = "Joe";echo $names[1] . " and " . $names[2] .
" are ". $names[0] . "'s neighbors";
?>
The code above will output:
Quagmire and Joe are Peter's neighbors
--------------------------------------------------------------------------------
Associative Arrays
An associative array, each ID key is associated with a value.
When storing data about specific named values, a numerical array is not always the best way to do it.
With associative arrays we can use the values as keys and assign values to them.
Example 1
In this example we use an array to assign ages to the different persons:
$ages = array("Peter"=>32, "Quagmire"=>30, "Joe"=>34);
Example 2
This example is the same as example 1, but shows a different way of creating the array:
$ages['Peter'] = "32";
$ages['Quagmire'] = "30";
$ages['Joe'] = "34";
The ID keys can be used in a script:
$ages['Quagmire'] = "30";
$ages['Joe'] = "34";echo "Peter is " . $ages['Peter'] . " years old.";
?>
The code above will output:
Peter is 32 years old.
--------------------------------------------------------------------------------
Multidimensional Arrays
In a multidimensional array, each element in the main array can also be an array. And each element in the sub-array can be an array, and so on.
Example
In this example we create a multidimensional array, with automatically assigned ID keys:
$families = array
(
"Griffin"=>array
(
"Peter",
"Lois",
"Megan"
),
"Quagmire"=>array
(
"Glenn"
),
"Brown"=>array
(
"Cleveland",
"Loretta",
"Junior"
)
);
The array above would look like this if written to the output:
Array
(
[Griffin] => Array
(
[0] => Peter
[1] => Lois
[2] => Megan
)
[Quagmire] => Array
(
[0] => Glenn
)
[Brown] => Array
(
[0] => Cleveland
[1] => Loretta
[2] => Junior
)
)
Example 2
Lets try displaying a single value from the array above:
echo "Is " . $families['Griffin'][2] .
" a part of the Griffin family?";
The code above will output:
Is Megan a part of the Griffin family?
--------------------------------------------------------------------------------
What is an array?
When working with PHP, sooner or later, you might want to create many similar variables.
Instead of having many similar variables, you can store the data as elements in an array.
Each element in the array has its own ID so that it can be easily accessed.
There are three different kind of arrays:
Numeric array - An array with a numeric ID key
Associative array - An array where each ID key is associated with a value
Multidimensional array - An array containing one or more arrays
--------------------------------------------------------------------------------
Numeric Arrays
A numeric array stores each element with a numeric ID key.
There are different ways to create a numeric array.
Example 1
In this example the ID key is automatically assigned:
$names = array("Peter","Quagmire","Joe");
Example 2
In this example we assign the ID key manually:
$names[0] = "Peter";
$names[1] = "Quagmire";
$names[2] = "Joe";
The ID keys can be used in a script:
$names[1] = "Quagmire";
$names[2] = "Joe";echo $names[1] . " and " . $names[2] .
" are ". $names[0] . "'s neighbors";
?>
The code above will output:
Quagmire and Joe are Peter's neighbors
--------------------------------------------------------------------------------
Associative Arrays
An associative array, each ID key is associated with a value.
When storing data about specific named values, a numerical array is not always the best way to do it.
With associative arrays we can use the values as keys and assign values to them.
Example 1
In this example we use an array to assign ages to the different persons:
$ages = array("Peter"=>32, "Quagmire"=>30, "Joe"=>34);
Example 2
This example is the same as example 1, but shows a different way of creating the array:
$ages['Peter'] = "32";
$ages['Quagmire'] = "30";
$ages['Joe'] = "34";
The ID keys can be used in a script:
$ages['Quagmire'] = "30";
$ages['Joe'] = "34";echo "Peter is " . $ages['Peter'] . " years old.";
?>
The code above will output:
Peter is 32 years old.
--------------------------------------------------------------------------------
Multidimensional Arrays
In a multidimensional array, each element in the main array can also be an array. And each element in the sub-array can be an array, and so on.
Example
In this example we create a multidimensional array, with automatically assigned ID keys:
$families = array
(
"Griffin"=>array
(
"Peter",
"Lois",
"Megan"
),
"Quagmire"=>array
(
"Glenn"
),
"Brown"=>array
(
"Cleveland",
"Loretta",
"Junior"
)
);
The array above would look like this if written to the output:
Array
(
[Griffin] => Array
(
[0] => Peter
[1] => Lois
[2] => Megan
)
[Quagmire] => Array
(
[0] => Glenn
)
[Brown] => Array
(
[0] => Cleveland
[1] => Loretta
[2] => Junior
)
)
Example 2
Lets try displaying a single value from the array above:
echo "Is " . $families['Griffin'][2] .
" a part of the Griffin family?";
The code above will output:
Is Megan a part of the Griffin family?
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