Python: How do I get this function to print?

#integers to be input
n = input('Enter \"n\" trials')
x = input('Enter \"x\" number of succeses')
p = input('Enter the probability \"p\" of success on a single trial')

#Probability Distribution function
def probDist(n, x, p):
    q = (1-p)**(n-x)
    numerator = math.factorial(n);
    denominator = math.factorial(x)* math.factorial(n-x);
    C = numerator / denominator;
    answer = C*p**x*q;

    return answer

# Does this have to come after I define the function? Or does this matter in Python
# Also this part just doesn't work.
dist = probDist(n, x, p);
print(dist);

Here's the error that I get after I run and I input all the values.

Traceback (most recent call last):
   line 17, in <module>
    开发者_C百科dist = probDist(n, x, p);
  line 9, in probDist
    q = (1-p)**(n-x)
TypeError: unsupported operand type(s) for -: 'int' and 'str'

In Python 3.x, input always returns a string, without applying eval the the user input. Python 2.x input does eval, but that's rarely what you want. If you want an integer, use int(input(...)) and if you want a float (not quite the same as a real number, as it has only limited range!), use float(input). (You should propably catch ValueError to handle the cases where the input is not appropiate; if this is for exercise/education, it's propably okay to leave error handling out for now.)

Does this have to come after I define the function?

Yes.

q = (1-p)**(n-x)

TypeError: unsupported operand type(s) for -: 'int' and 'str'

You have two - operations. One of those two is a mixture of int and str data.

Let's go through each operand.

1 - int

p - result of input(), and therefore a string

n - result of input(), and therefore a string

x - result of input(), and therefore a string

You probably want to do something to convert the results of input() to a proper floating-point value. float() works well for this.