CHECK / BOOL :
bool filter_var(var, filter) : check filter
filter=FILTER_VALIDATE_URL
bool in_array(el, arr) : if el in array arr
bool is_array(val) : if val is array
bool isset() : ?
bool pregmatch(regex, str) : match regex on str
VAR HANDLING :
string create_function(str args, str code) : create a function with args and given code,
and return a unique name for it
array parse_url(url) : return array, where each element is a part of url (if present)
ARRAY :
array array_merge(arr1, …) : return merge of all arrays
array_pop(arr) : remove and return last element
element array_shift(arr) : remove and return first element
array array_unshift(arr, el1, …) : add [el1, …] to beginning of array;
return the array
int count(arr) : length of array
string implode(str, arr) : return a string, containing array elements joined by string str
unset(arr[key]) : remove array element at key
CURRENT :
string $_GET[‘par’] : value of current page’s url parameter par
URIs :
string file_get_contents(path) : get content of link or local file
I/O :
die(string) : print error string
echo(string) : print string