Week 2

All the function learnt this week - Week 2

if  : 
The if function is used when you are asking a question or statement and you want a specific reply to each answer. With this you have to be careful with the indentation making sure they line up with your programming, otherwise your coding wont work.
Example -
food = input("What food do you like? ")   ----or--         raining = input("Is it raining (yes/no)? ")
if food == "cake":                                                            if raining == "yes":
  print("Wow, I love cake too!")                                        print("You should take the bus to work.")
  print("Did I tell you I like cake?")                                 if raining == "no":
                                                                                           print("You should walk to work.")

Nothing appearing :
When you want to make sure nothing appears other than the coding use empty quotations at the end of your code .
 Example -
text= input("Text: ")
if text == "Marco!":
  print("Polo!")
  if text == "":
    print("")

True/ False:

In python they use true and false with if functions and other parts of the coding.
 Example -
x = 3
print(x > 10)
False
Else :       
Else is better for simplifying if because you can use it to apply a certain answer to any other input other than the expected answer.
Example -
raining = input("Is it raining (yes/no)? ")
if raining == "yes":
  print("You should take the bus to work.")
else:
  print("You should walk to work.")

- Comparing : 
In else you can use operations to compare. This is available because the program wont always make sense so with these you can make it conditional to the coding.

Operation	Operator
equal to	==
not equal to	!=
less than	<
less than or equal to	<=
greater than	>
greater than or equal to	>=

Example -
x = 5
if Charge <=5:
  print("Connect your charger!")
else:
    print("All good.")

Decisions with multiple options (elif): 

When you need to make more than one option you can use else and if to create the other option but it can get a bit mess or instead you can use elif as a abbreviation 

Example - 

Using elif                                                        Not using elif 

x = 5                                                              else: 

if x < 3:                                                            if x == 3:

  print("x is less than three")                             print("x is equal to three")

elif x == 3:

  print("x is equal to three")

else:

  print("x is greater than three")

String within a string
Example -
msg = 'hello world' 
print('h' in msg) 
True 

Sub string within a string
Example -
msg = 'concatenation is fun'
print('cat' in msg) 
print('dog' in msg)
True
False

Making Decisions 
Using if with a variable/string means you limit what you are looking for.
Example -
name = input('Enter your name? ') 
if 'x' in name:
  print('Your name contains an x!')
else:
  print('No "x" in your name.') 

String Methods 
Changing to lowercase:
Example -
msg = "I know my ABC" 
print(msg.lower())
or
msg = "I know my ABC" 
newmsg = msg.lower()
print(newmsg)
Changing to uppercase:
msg = "I know my ABC" 
newmsg = msg.upper()
print(newmsg)
or
For printing statements:
msg = "I know my ABC"
print("Original:", msg)
print("Lowercase:", msg.lower())
print("Uppercase:", msg.upper())
Original: I know my ABC
Lowercase: i know my abc
Uppercase: I KNOW MY ABC

Checking the case:
Example -
msg = "a lowercase string!" 
print(msg.islower()) 
print(msg.isupper())

For first letter capital and rest not use name.capitalize():
name = input('Enter your name: ') 
print('Name converted to:', name.capitalize())
Enter your name: XAVIER
Name converted to: Xavier

Replacing String 

Using this function will let you replace parts of the string.
Example -
msg = 'hello world'
print(msg.replace('l', 'X'))
heXXo worXd
or
msg = 'hello world'
msg = msg.replace('hello', 'goodbye')
msg = msg.replace('o', 'X')
print(msg)
gXXdbye wXrld
Counting Characters in a string 
This will check how many characters are in that string you an also use double letter such as ll.
Example -
msg = "hello world" 
print(msg.count("l"))
3