Several useful PHP string filtering and conversion function codes

nl2br();// n to

addslashes(); stripslashes();//Escape special characters when operating on the database

chop();//Remove spaces on the right side of the string
trim();// Remove all spaces in the string
ltrim();//Remove the spaces on the left side of the string

htmlspecialchars();//Convert '$','"','<','>' to the corresponding html entities
htmlentities();//Convert all html tags into corresponding html entities

array explode(string separator, string str);//Split the string
string implode(string separator, array arr);//Connect the string

strtoupper(); strtolower();//Convert uppercase to uppercase
ucfirst();//Convert only the first character to uppercase
ucwords();//Convert the first letter of each word to uppercase