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PHP Script Tips - Understanding String Literals and Operations

By: FYICenter.com

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(Continued from previous part...)

How Many Ways to Include Variables in Double-Quoted Strings?

There are 3 formats to include variables in double-quoted strings:

• "part 1 $variable part 2" - This is the simplest format to include a variable in a string. The variable name starts with the dollar sign and ends at the first character that can not be used in variable name. Space is good character to end a variable name.
• "part 1${variable}part 2" - This format helps you to clearly end the variable name. The variable name starts at dollar sign before the open brace (${) and ends at the close brace (}).
• "part 1{$variable}part 2" - This format is also called complex format. You use this format to specify any complex variable expression in the same way as in a normal statement. The variable expression starts at ({$) followed by a variable name and ends at (}).

Here is a PHP script example of different ways to include variables in double-quoted strings:

<?php 
$beer = 'Heineken';
echo "$beer's taste is great.\n";
echo "He drank some ${beer}s and water.\n"; 
echo "She drank some {$beer}s and water.\n"; 
?>

This script will print:

Heineken's taste is great.
He drank some Heinekens and water.
She drank some Heinekens and water.

How Many Ways to Include Array Elements in Double-Quoted Strings?

There are 2 formats to include array elements in double-quoted strings:

• "part 1 $array[key] part 2" - This is called simple format. In this format, you can not specify the element key in quotes.
• "part 1 {$array['key']} part 2" - This is called complex format. In this format, the array element expression is specified in the same way as in a normal statement.

Here is a PHP script example of different ways to include variables in double-quoted strings:

<?php 
$fruits = array('strawberry' => 'red', 'banana' => 'yellow');
echo "A banana is $fruits[banana].\n";
echo "A banana is {$fruits['banana']}.\n";
?>

This script will print:

A banana is yellow.
A banana is yellow.

"A banana is $fruits['banana'].\n" will give you a syntax error.

How To Access a Specific Character in a String?

Any character in a string can be accessed by a special string element expression:

• $string{index} - The index is the position of the character counted from left and starting from 0.

Here is a PHP script example:

<?php 
$string = 'It\'s Friday!';
echo "The first character is $string{0}\n"; 
echo "The first character is {$string{0}}\n"; 
?>

This script will print:

The first character is It's Friday!{0}
The first character is I

How To Assigning a New Character in a String?

The string element expression, $string{index}, can also be used at the left side of an assignment statement. This allows you to assign a new character to any position in a string. Here is a PHP script example:

<?php 
$string = 'It\'s Friday?';
echo "$string\n";
$string{11} = '!';
echo "$string\n";
?>

This script will print:

It's Friday?
It's Friday!

(Continued on next part...)

Part:   1  2   3  4