PHP- String function explanation

All String Functions in PHP
str_replace: How to replace a part of a string with another string
str_ireplace: Case in-sensitive search and replace using array of strings
strlen: How to find length of a string in PHP?
trim: Removing empty space from both sides of a string
strrev: Reversing a string by using strrev function in PHP
Adding two or more strings in PHP
stristr: Searching for a presence of a string inside another string
nl2br: Adding Line breaks inside a string in place of carriage returns
split: Breaking a string to form array using delimiters
substr: Collecting part of a string
substr_count: Counting occurrence of sub string in main string
str_repeat: Repeating a string number of times
strtolower(): function to change alphabets to Lower case
strtoupper(): function to change characters to upper case letters
function to collect part of a string with two landmarks
Random string generator with number and alphabets for password
strcasecmp(): Case insensitive string comparison
strcmp(): Case sensitive string comparison
str_pad(): String pad with specified length
md5 hash of a string: encryption of a string
Separating domain and userid part from an email address using split
htmlspecialchars: Printing html special chars to the page
strip_tags: Removing html tags within a string
ucwords: Converting first letter of every word to UpperCase