A string is sequence of character.
Every thing that is declared in a string will considered as a character.

Like abcd1234 is a string.

And when you add the string like 2+2 will give 22 not 4.

PHP string function

strlen()- It is used to find the length of the string. It can also count the number of spaces and character.

ex-

<?php
echo strlen("Hello people"); // outputs 12
?>

str_word_count()- It is used to count the number of word that are there in the string. It count the word after the space. So in short the number of spaces with addition of 1 can give your number of word.

ex-

<?php
echo str_word_count("Hello people"); // outputs 2
?>

strrev()- It is use to get the reverse of a string.

ex-

<?php
echo strrev("Hello people"); // outputs elpoep olleH
?>

strpos()- It is use to search a specific word or string in a given string. It returned 6 because the first letter of the search string is found on the 6 place.

<?php
echo strpos("Hello people", "people"); // outputs 6
?>

str_replace()- It is use to replace the string with another string.

ex-

<?php
echo str_replace("people", "girls", "Hello people"); // outputs Hello girls
?>