Reading a multi-byte number

[Batista, Facundo]

I must read a 8bit number from a file. This is easy:

caract = myfile.read(1)
number = ord(caract)

But when I must read a 16bit number it's a little more complicated:

(caract1, caract2) = myfile.read(2)
number = ord(caract1) * 255 + ord(caract2)

When I must read a (8 * n)bit number, I need a for (this code it's not
tested):

def strInt(cadena):
        exponentes =  range(len(cadena)-1, -1, -1)
        valor = 0
        for ind in range(len(cadena)):
                car = cadena[ind]
                exp = exponentes[ind]
                valor += ord(car) * (255 ^ exp)
        return valor


There's a builtin way to do this?

Thank you!

.	Facundo