String Variables in PHP

A string is a sequence of characters enclosed within quotes.

Exam Definition: A string is a collection of characters stored inside single or double quotes.

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Declaration Styles of String Variables

PHP supports multiple ways to declare string variables.

1. Single-Quoted Strings

• Variables are not parsed
• Faster than double quotes

$str = 'Welcome to PHP';
echo $str;

$name = 'Rohit';
echo 'Hello $name';   // Output: Hello $name

Exam Point: Single quotes treat variables as plain text.

2. Double-Quoted Strings

• Variables are parsed
• Escape sequences are supported

$name = "Rohit";
echo "Hello $name";   // Output: Hello Rohit

Escape Sequences Example

echo "Line1\nLine2";

Exam Tip: Use double quotes when variable parsing is required.

3. Concatenation of Strings

Concatenation means joining strings using dot (.) operator.

$fname = "Rohit";
$lname = "Kumar";
echo $fname . " " . $lname;

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Heredoc Style

Heredoc is used to write multi-line strings easily.

Syntax

$str = <<<TEXT
This is a
multi-line
string
TEXT;

Heredoc with Variables

$name = "PHP";

$str = <<<DATA
Welcome to $name Programming
DATA;

echo $str;

Features

• No need for quotes
• Variables are parsed
• Useful for HTML output

Exam Definition: Heredoc allows writing multi-line strings without escape characters.

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String Functions in PHP

PHP provides many built-in string functions for manipulation.

Commonly Used String Functions

1. strlen()

Returns string length.

echo strlen("PHP");

2. str_word_count()

Counts words in a string.

echo str_word_count("Welcome to PHP");

3. strtoupper()

Converts to uppercase.

echo strtoupper("php");

4. strtolower()

Converts to lowercase.

echo strtolower("PHP");

5. ucfirst()

Capitalizes first character.

echo ucfirst("php");

6. substr()

Extracts part of a string.

echo substr("Programming", 0, 4);

7. str_replace()

Replaces text.

echo str_replace("PHP", "Java", "PHP is easy");

8. trim()

Removes whitespace.

echo trim("  PHP  ");

9. strpos()

Finds position of a word.

echo strpos("Learn PHP", "PHP");

Summary Table: String Functions

Exam Tip: String functions simplify text manipulation.