PHP : Strings

In PHP, strings are sequences of characters enclosed within either single quotes (`'`) or double quotes (`"`). Strings can contain alphanumeric characters, symbols, whitespace, and escape sequences. Here's an overview of working with strings in PHP:

1. Defining Strings:

Single-quoted strings: Enclosed within single quotes, escape sequences are not interpreted, and variables are not interpolated.

$string1 = 'Single-quoted string';

Double-quoted strings: Enclosed within double quotes, escape sequences are interpreted, and variables are interpolated.

$string2 = "Double-quoted string";

2. String Concatenation:

Strings can be concatenated using the `.` operator.

$name = "John"; $greeting = "Hello, " . $name . "!";

3. Escape Sequences:

Escape sequences allow you to include special characters within strings. Some common escape sequences include:

`\"`: Double quote
`\'`: Single quote
`\\`: Backslash
`\n`: Newline
`\t`: Tab

Example:

$escapedString = "This is a \"quoted\" string with\na newline.";

4. String Interpolation:

Double-quoted strings allow variable interpolation, meaning that variables within the string are replaced with their values.

  $name = "John"; $greeting = "Hello, $name!";

5. String Functions:

PHP provides a variety of string functions for manipulating and working with strings. Some common string functions include:

strlen(): Returns the length of a string.
strpos(): Returns the position of the first occurrence of a substring within a string.
substr(): Returns a substring of a string.
str_replace(): Replaces all occurrences of a substring within a string.
strtolower(), strtoupper(): Converts a string to lowercase or uppercase.
trim(): Removes whitespace or other specified characters from the beginning and end of a string.

Example:

$string = "Hello, world!"; $length = strlen($string); // Returns 13 $position = strpos($string, "world"); // Returns 7 $substring = substr($string, 0, 5); // Returns "Hello"