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PHP Script Tips - Understanding String Literals and Operations

By: FYICenter.com

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A collection of 14 tips on PHP string literals, operations and conversaion. Clear explanations and tutorial exercises are provided on single-quoted strings, double-quoted strings, string elements, concatenation, converting values to strings, converting strings to values. Topics included in this collections:

1. What Are the Special Characters You Need to Escape in Single-Quoted Stings?
2. Can You Specify the "new line" Character in Single-Quoted Strings?
3. How Many Escape Sequences Are Recognized in Single-Quoted Strings?
4. What Are the Special Characters You Need to Escape in Double-Quoted Stings?
5. How Many Escape Sequences Are Recognized in Double-Quoted Strings?
6. How To Include Variables in Double-Quoted Strings?
7. How Many Ways to Include Variables in Double-Quoted Strings?
8. How Many Ways to Include Array Elements in Double-Quoted Strings?
9. How To Access a Specific Character in a String?
10. How To Assigning a New Character in a String?
11. How To Concatenate Two Strings Together?
12. How To Compare Two Strings with Comparison Operators?
13. How To Convert Numbers to Strings?
14. How To Convert Strings to Numbers?

What Are the Special Characters You Need to Escape in Single-Quoted Stings?

There are two special characters you need to escape in a single-quote string: the single quote (') and the back slash (\). Here is a PHP script example of single-quoted strings:

<?php 
echo 'Hello world!'; 
echo 'It\'s Friday!'; 
echo '\\ represents an operator.'; 
?>

This script will print:

Hello world!It's Friday!\ represents an operator.

Can You Specify the "new line" Character in Single-Quoted Strings?

You can not specify the "new line" character in a single-quoted string. If you don't believe, try this script:

<?php 
echo '\n will not work in single quoted strings.'; 
?>

This script will print:

\n will not work in single quoted strings.

How Many Escape Sequences Are Recognized in Single-Quoted Strings?

There are 2 escape sequences you can use in single-quoted strings:

• \\ - Represents the back slash character.
• \' - Represents the single quote character.

What Are the Special Characters You Need to Escape in Double-Quoted Stings?

There are two special characters you need to escape in a double-quote string: the double quote (") and the back slash (\). Here is a PHP script example of double-quoted strings:

<?php 
echo "Hello world!"; 
echo "Tom said: \"Who's there?\""; 
echo "\\ represents an operator."; 
?>

This script will print:

Hello world!Tom said: "Who's there?"\ represents an operator.

How Many Escape Sequences Are Recognized in Double-Quoted Strings?

There are 12 escape sequences you can use in double-quoted strings:

• \\ - Represents the back slash character.
• \" - Represents the double quote character.
• \$ - Represents the dollar sign.
• \n - Represents the new line character (ASCII code 10).
• \r - Represents the carriage return character (ASCII code 13).
• \t - Represents the tab character (ASCII code 9).
• \{ - Represents the open brace character.
• \} - Represents the close brace character.
• \[ - Represents the open bracket character.
• \] - Represents the close bracket character.
• \nnn - Represents a character as an octal value.
• \xnn - Represents a character as a hex value.

How To Include Variables in Double-Quoted Strings?

Variables included in double-quoted strings will be interpolated. Their values will be concatenated into the enclosing strings. For example, two statements in the following PHP script will print out the same string:

<?php 
$variable = "and";
echo "part 1 $variable part 2\n"; 
echo "part 1 ".$variable." part 2\n"; 
?>

This script will print:

part 1 and part 2
part 1 and part 2

(Continued on next part...)

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