Unit 1: Python fundamentals

Python was created by Guido van Rossum and released in 1991. It is interpreted, high-level, dynamically typed and object-oriented, with readable syntax that uses indentation instead of braces. Application areas: web development (Django, Flask), data science and machine learning (NumPy, pandas, scikit-learn), automation and scripting, desktop apps, game development and IoT.

• Identifiers start with a letter or underscore and are case-sensitive; keywords (if, else, for, while, def, return, class, import, True, False, None …) are reserved.

• Operators: arithmetic (+, −, ×, /, // floor division, % modulus, ** power), comparison, logical (and, or, not), membership (in, not in) and identity (is, is not).
• Type conversion: int("5"), float(3), str(10).
• Input/output: name = input("Enter name: ") (always returns a string) and print("Hello", name, sep=" ", end="\n").

Strings are immutable sequences of characters.

pythons = "Python Programming"
print(s[0], s[-1])        # P g
print(s[0:6])             # Python   (slicing: start included, end excluded)
print(s[::-1])            # reversed string
print(s.upper(), s.lower(), s.split(), s.replace("Python", "C"))
print(len(s), s.find("Pro"), s.count("m"))
name, marks = "Ana", 91.5
print(f"{name} scored {marks:.1f}")      # f-string formatting

pythonn = int(input("Number: "))
if n % 2 == 0:
    print("Even")
else:
    print("Odd")

for i in range(1, 6):     # 1 to 5
    if i == 3:
        continue          # skip 3
    print(i)

while True:
    x = int(input())
    if x < 0:
        break             # exit the loop

• pass is a placeholder that does nothing; exit() (sys.exit) ends the program.
• range(start, stop, step) generates numbers up to but not including stop.