Alternative Execution

Else

We may want to run something else when the if check fails
This can be accomplished using else

Example

if x % 2 == 0 :
    print('x is even')
else :
    print('x is odd')

else control flow diagram

Example

small_num = input("Enter a number:")
big_num = input("Enter a bigger number:")

if small_num < big_num:
    print("You entered the numbers correctly")
else:
    print("Your second number is too small")

Chained Conditionals

We may want more than two branches of execution
We can chain multiple conditionals to achieve this

Chained Conditionals

if x < y:
    print('x is less than y')
elif x > y:
    print('x is greater than y')
else:
    print('x and y are equal')

elif control flow diagram

Improved printing

The print function will accept multiple items to print
Items must be separated by commas

Print Example

print("Hello world!")
print("A few numbers: ", 1, 2, 3)

Printing a name

name = input("What is your name?")
print("Hello", name)

Basic string operations

Concatenation can be performed using the + operator
Duplication can be performed using the * operator
Comparison can be performed using standard comparison operators

Example

word1 = input("Enter a word:")
word2 = input("Enter another word:")

if word1 < word2:
    print(word1, "comes before", word2, "alphabetically")
elif word1 > word2:
    print(word1, "comes after", word2, "alphabetically")
else:
    print(word1, "and", word2, "are the same word")