Demo Code for Iteration

loops.py

print("Loop Demos")

# i = 5
# while i < 5:
#     print (str(i) + "!")
#     i+=1 #(i = i+1)
# print("All done.")


# i = 5
# while i < 5:
#     print (str(i) + "!")
#     i+=1 #(i = i+1)
#     if (i <4 ):
#          break
# else:
#     print("All done.")

# for c in "AJ Armstrong":
#     print(c)

# for x in range(10,0,-1):
#     print(x)

# for x in range(1,int(1e6),10):
#     if x%51 == 0:
#         break
#     elif x%31 == 0:
#         continue
#     print (str(x) + ", ", end='')

#Prime Number Search
#Prints primes in range 2 to argument
def primes(x):
    DEBUG=True #Use to change output style
    if x < 2 :
        print("There are no prime numbers less than 2.")
    for p in range(2,x):
        if DEBUG:print("Prime Candidate:" + str(p))
        prime=True # Assume prime, then start looking for factors
        #Free number theory lecture: If there are no factors
        #of p less than or equal to the square root of p (math.sqrt(p))
        #then p is prime.
        for f in range(2,int(math.ceil(math.sqrt(p)))):
            #Did I find a factor on a previous loop iteration?
            if not prime:
                break

            if DEBUG:print("  Checking possible factor: " + str(f))
            #is f a factor of p?
            if(p%f==0): #if no remainder for f/p, f is a factor of p
                if DEBUG:print("  " + str(p) + " is not prime.")
                prime=False
                #no point in carrying on, we know this isn't prime
                continue

        if prime:
            if DEBUG:
                print("*** " + str(p) + " is prime. ***" )
            else:
                print(str(p) + " ", end="")

    print() # Make sure a blank line at the end of output.

primes(100)