#!/usr/bin/env python
# coding: utf-8

# # Review of control flow / basic for loops

# In[1]:


# Fill in based off of confusion from yesterday


# # Advanced for loop keywords

# In[6]:


# This is a reminder of what a loop looks like

for i in range(20):
    print(i)
print('Loop completed!')


# In[7]:


# There are two keywords for loops that you will need to know
# The first is "break"
# Notice "break" is in green
# Break will exit a for loop once it is executed

for i in range(20):
    if i == 10:
        break
    print(i)
print('Loop completed!')


# In[8]:


# The other keyword you need to know is "continue"
# "continue" will make it so that the rest of the loop body is not executed
# but ONLY for the time it is called
# Notice that "10" is not printed

for i in range(20):
    if i == 10:
        continue
    print(i)
print('Loop completed!')


# In[9]:


# You can have continue and break in the same loop

for i in range(20):
    if i == 10:
        continue
    if i == 15:
        break
    print(i)
print('Loop completed!')


# # While loops

# In[ ]:


# This is the generic syntax for a while loop

while CONTIDION:
    LOOP_BODY


# In[10]:


# A "while loop" is a loop that executes while CONDITION is true
# The CONDITION is evaluated once the loop body finishes, and only then

i = 0
while i < 10:
    print(i)
    i += 1
print('Loop completed!')


# In[1]:


# If CONDITION is False at the start of the loop, the loop body will not execute!

i = 0
while i < 0:
    print(i)
    i += 1
print('Loop completed!')


# In[12]:


# What is different about this and the one two above?

i = 0
while i < 10:
    i += 1
    print(i)
print('Loop completed!')


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# WARNING!!!!
# You can have loops that run forever.
# These are really really bad.
# Make sure the loop terminates.

while True:
    print('hi!')


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# WARNING!!!!!
# Even if you don't mean to, the loop can run forever.
# DO NOT do this.

i = 0
while i < 10:
    print(i)
print('Loop completed!') # This will never execute!


# In[18]:


# You can use "continue" in while loops
# The syntax and behavior is exactly the same as in for loop

i = 0
while i < 10:
    i += 1
    if i == 5:
        continue
    print(i)
print('Loop completed!')


# In[19]:


# WARNING!!!!
# This loop will also run forever. Why?
# Don't do this.

i = 0
while i < 10:
    if i == 5:
        continue
    print(i)
    i += 1
print('Loop completed!')


# In[20]:


# You can also use "break" in while loops
# The syntax and usage is exactly the same as in for loops

i = 0
while True:
    if i > 10:
        break
    print(i)
    i += 1


# In[21]:


# What will happen?

i = 0
while True:
    i += 1
    if i > 10:
        break
    print(i)


# # Functions (variable scoping)

# In[2]:


# WARNING!!!
# Variables are "scoped"
# This is a complex topic, and we won't have time to cover all of it in lecture
# We will only cover the basics: variables inside a function
# Variables inside a function have no relation to variables outside the function
# See what happens when "i" is printed inside and outside the function

i = 0
def func(x):
    i = 10
    print(i, x)
    
func(5)
print(i)


# In[23]:


# Variables across functions have no relation to each other
# A variable declared inside a function will have no relation to outside the function
# Why is there an error?

def func1(x):
    j = 10
    print(j, x)
    
def func2(x):
    j = 5
    func1(x)
    print(x)
    
func2(3)
print(j)


# In[24]:


# WARNING: Indentation is not the same scoping
# Scoping only applies to functions
# If blocks, for loops, and while loops ARE NOT functions

i = 0
for i in range(3):
    print(i)


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# Why is this the output?

k = 0
for i in range(3):
    print(k)


# In[26]:


# How about here?

k = 0
for i in range(3):
    k = 6
    print(k)


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