PHP - For Loop

PHP - For Loop

The for loop is simply a while loop with a bit more code added to it. The common tasks that are covered by a for loop are:

Set a counter variable to some initial value.

Check to see if the conditional statement is true.

Execute the code within the loop.

Increment a counter at the end of each iteration through the loop.

The for loop allows you to define these steps in one easy line of code.
It may seem to have a strange form, so pay close attention to the syntax used!

For Loop Example

Let us take the example from the while loop lesson and see how
it could be done in a for loop. The basic structure of the for loop is as
follows:

Pseudo PHP Code:

for ( initialize a counter; conditional statement; increment a counter){
 do this code;
}

Notice how all the steps of the loop are taken care of in the for loop
statement. Each step is separated by a semicolon: initiliaze counter, conditional statement, and the
counter increment. A semicolon is needed because these are separate expressions. However, notice
that a semicolon is not needed after the "increment counter" expression.
Here is the example of the brush prices done with a for loop .

PHP Code:

$brush_price = 5; 

echo "<table border=\"1\" align=\"center\">";
echo "<tr><th>Quantity</th>";
echo "<th>Price</th></tr>";
for ( $counter = 10; $counter <= 100; $counter += 10) {
 echo "<tr><td>";
 echo $counter;
 echo "</td><td>";
 echo $brush_price * $counter;
 echo "</td></tr>";
}
echo "</table>";

Display:

Quantity	Price
10	50
20	100
30	150
40	200
50	250
60	300
70	350
80	400
90	450
100	500

It is important to note that both the for loop and while loop
implementation of the price chart table are both OK at getting the job done. However,
the for loop is somewhat more compact and would be preferable in this situation. In
later lessons we will see where the while loop should be used instead of the for loop.

PHP For Each Loop

Imagine that you have an associative array that you want to iterate through. PHP provides an easy way to use every element of an array with the Foreach statement.

In plain english this statement will do the following:

• For each item in the specified array execute this code.

While a For Loop and
While Loop will continue
until some condition fails, the For Each loop will continue until
it has gone through every item in the array.

PHP For Each: Example

We have an associative array that stores the names of people in our
company as the keys with the values being their age. We want
to know how old everyone is at work so we use a Foreach loop to print
out everyone's name and age.

PHP Code:

$employeeAges;
$employeeAges["Lisa"] = "28";
$employeeAges["Jack"] = "16";
$employeeAges["Ryan"] = "35";
$employeeAges["Rachel"] = "46";
$employeeAges["Grace"] = "34";

foreach( $employeeAges as $key => $value){
 echo "Name: $key, Age: $value <br />";
}

Display:

Name: Lisa, Age: 28

Name: Jack, Age: 16

Name: Ryan, Age: 35


Name: Rachel, Age: 46

Name: Grace, Age: 34

The syntax of the foreach statement is a little strange, so let's talk about it some.

Foreach Syntax: $something as $key => $value

This crazy statement roughly translates into: For each element of the
$employeeAges associative array I want to refer to the key as $key and the value as $value.

The operator "=>" represents the relationship between a key and value. You can imagine that
the key points => to the value. In our example we named the key $key and the value $value.
However, it might be easier to think of it as $name and $age. Below our example does this and notice how the output
is identical because we only changed the variable names that refer to the keys and values.

PHP Code:

$employeeAges;
$employeeAges["Lisa"] = "28";
$employeeAges["Jack"] = "16";
$employeeAges["Ryan"] = "35";
$employeeAges["Rachel"] = "46";
$employeeAges["Grace"] = "34";

foreach( $employeeAges as $name => $age){
 echo "Name: $name, Age: $age <br />";
}

Display:

Name: Lisa, Age: 28

Name: Jack, Age: 16


Name: Ryan, Age: 35

Name: Rachel, Age: 46

Name: Grace, Age: 34