Python Syntax, Variables, and Control Flow

Python reads closer to plain English than most languages, which is exactly why it is a common first language - but it still has real rules underneath that simplicity.

Variables need no type declaration

Unlike Java, Python figures out a variable's type automatically from the value you assign:

name = "Riya"           # a string
age = 21                # an integer
price = 19.99           # a float
is_student = True       # a boolean

Indentation is not optional

Python uses indentation (not curly braces) to define blocks of code. Get the indentation wrong and your program will not run - this trips up almost everyone in their first week:

if age >= 18:
    print("You can vote")   # this line must be indented
    print("Welcome!")        # so must this one
else:
    print("Not yet")

if / elif / else

marks = 78
if marks >= 90:
    print("Grade A")
elif marks >= 75:
    print("Grade B")
else:
    print("Grade C or below")

Loops

# for: loop over a known range or collection
for i in range(5):
    print("Count:", i)

# while: loop until a condition changes
attempts = 0
while attempts < 3:
    print("Attempt", attempts)
    attempts += 1

Python has no i++ shorthand - use i += 1 instead. This is a small but common trip-up if you are coming from another language.