PHP Miscellaneous functions. so you can see below the following functions.
|define()||The define() function defines a constant. A constant’s value cannot be changed after it isset. the constant name does not need a leading dollar sign.|
|constant()||The constant() function returns the value of a constant. this function also works with class constants.|
|include()||The include() takes all the text in a specified file and copies it into the file that uses the include function.|
|require()||The require() function is identical to include(), except that it handles errors differently.|
|header()||The header() function sends a raw HTTP header to a client. it is important to notice that header() must be called before any actual output is sent.|
|die()||The die() function prints a message and exits the current script. this function is an alias of the exit() function.|