Unit 2: Creating Python Programs

Learning Outcomes

Use identifiers, keywords and literals correctly
Form expressions using Python operators
Read input and produce formatted output
Define functions and use control structures

Identifiers, Keywords and Literals

Identifiers name variables and functions and follow Python naming rules; keywords are reserved words. Literals include numbers and strings, and Python is dynamically typed so no explicit type declaration is needed.

age = 21        # integer literal
pi = 3.14159    # float literal
name = "Asha"   # string literal

Operators and Expressions

Python provides arithmetic, relational, logical, assignment, membership and identity operators. Expressions combine operands with operators and are evaluated according to operator precedence.

a, b = 7, 3
print(a + b, a // b, a % b, a ** b)

Input and Output

The input function reads a string from the user and print displays output; f-strings format values cleanly within text.

n = int(input("Enter a number: "))
print(f"The square of {n} is {n*n}")

Functions and Control Structures

Functions are defined with def and may take default arguments and return values. Control flow uses if-elif-else and while or for loops with break, continue and pass; the exit function ends a program.

def is_even(n=0):
    return n % 2 == 0
for i in range(5):
    if is_even(i):
        print(i, "is even")

Summary

This unit covered identifiers and literals, operators and expressions, input and output, defining functions with default arguments, and the control structures of Python.

Exercises

Write a program to check whether a number is prime and to generate the first n prime numbers.
Write a program using a function to compute the factorial of a number.
Write a program to print a pyramid pattern of stars.

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