String functions in php. built-in string functions

php built-in string functions
chr() : Returns character from ascii val.
ord() : Returns ascii val from char.
Strtolower() : Convert into lower case.
Strtoupper() : Convert into upper case.
Strlen() : Return the length of string.
Ltrim() : Remove white space from left side.
Rtrim() : Remove white space from right side.
Trim() : Remove white space from both side.
Substr() : Returns sub string from given.
strcmp() : Compare two strings. (c-sensitive)
strcasecmp() : Compare two strings. (c-insensitive)
strpos() : Return position of 1st occurrence.
strstr() : Find 1st occurrence of str inside str.(CS)
stristr() : Find 1st occurrence of str inside str. (CIS)
Str_replace() : Replace the string.
strrev() : Reverse the string.