someone who knows list the functions related to this library?
thank you 
Did you look at the tutorial: Arduino Playground - Keypad Library ?
I will try to use them but the program does not compile properly.
For example I use this function: "char getKey () -Returns the key pressed That Is, if any. This function is non-blocking"
in this way:
char key = getKey ();
and so does not compile .. while the same function used in their example becomes:
char key = keypad.getKey ();
this is not the same thing. is not it? and why?
Yes, it is the same thing. The first one is from a listing of the keypad functions, but it actually says
char getKey()
Returns the key that is pressed, if any. This function is non-blocking.
meaning that the function getKey() returns a char.
The second is an example of using that function with the keypad object.
You must have an instance of the class to call the class methods on.
this is not the same thing. is not it?
No, it is not. It is the proper way to call the function.
and why?
Why what? Why does the example use proper code?
kanel:
I will try to use them but the program does not compile properly.
For example I use this function: "char getKey () -Returns the key pressed That Is, if any. This function is non-blocking"
in this way:char key = getKey ();
and so does not compile .. while the same function used in their example becomes:
char key = keypad.getKey ();
this is not the same thing. is not it? and why?
If you don't know the difference, you need to read basics of object oriented programming. There's endless tutorials on that topic. There is no point explaining the code to you before you understand the basic.
getkey() is part of keypad so to use it you use the calling convention keypad.getkey().
The reason? because that's the way it's done. Kind of like Serial. Serial.begin(9600) Serial.read() and so forth.