python - Function keeps doing the same thing -

this program suppose find 1000 prime numbers , pack them list

here's code:

num = raw_input('enter starting point') primes = [2] num = int(num) def prime_count(num):      if num % 2 == 0: #supposed check if number divided 2 evenly         num = num +1 #if is, add 1 number , check again         return num       elif num % num == 0:         primes.append(num) #supposed add prime list         num = num + 1 #add 1 , check again         return num   while len(primes) <= 999:     prime_count(num) 

so happens when run it: asks me raw_input , goes various things depending on choose input:

• if choose prime, let's 3, runs , adds 999 of 3s list instead of adding 1 time , going on try 4
• if choose non-prime, let's 4, breaks, after can't print out list

what doing wrong?

update: fixed it, when run i'm getting error (typeerror: unsupported operand type(s) %: 'nonetype' , 'int')

number = raw_input('enter starting point') primes = [2] number = int(number) def prime_count(x):      if x % 2 == 0: #supposed check if number divided 2 evenly         number = x +1 #if is, add 1 number , check again         return number        else:         in range(3, x-1):             if x % == 0:                 primes.append(x) #supposed add prime list                 number = x + 1 #add 1 , check again                 return number   while len(primes) <= 999:     number = prime_count(number) 

you're never using return value prime_count. try this:

while len(primes) <= 999:     num = prime_count(num) 

you've set self confusion using name num both parameter (also local variable) inside of prime_count, , global variable. though have same name, different variables, due python's rules scope of variables.

also, prime_count (probably unintentionally) leveraging fact primes global variable. since you're not assigning it, rather calling method (append), code work without using global keyword.

however, algorithm isn't correct. if num % num == 0 says "if number divided has remainder of zero" always true. program find lot of "primes" aren't primes.

real python programs little in global scope; current code asking confusion. suggest start template, , reading of existing python code.

def add_three(a_param):     a_local_var = 3       # *different* 1 in main!                           # changes variable *not* affect                           # identically-named variables in other functions      return a_local_var + a_param  def main():     a_local_var = 2      result = add_three(a_local_var)      print result    # prints 5  if __name__ == '__main__':     main()