Python Basics

Exercises

1. 1. Hello world with print

   Concept: print(). The function print() displays text. Write a script that outputs exactly Hello World.

   mkdir -p /home/student/python
   echo 'print("Hello World")' > /home/student/python/hallo.py
   python3 /home/student/python/hallo.py

   Check: python3 /home/student/python/hallo.py prints Hello World. The checker runs your script the same way.

2. 2. Variable + input

   Concept: variable. A variable stores a value under a name. With input() your program gets the value from the keyboard — so it greets everyone by their own name.

   nano /home/student/python/variable.py:

   name = input()
   print("Hello " + name)

   Test it: python3 /home/student/python/variable.py, type Mia and press Enter.

   Check: If you enter Mia, it prints Hello Mia. The checker tests with two different names — so a hard-coded greeting does not pass.

3. 3. A decision with if/else

   Concept: if/else. With if you test a condition; else is the case when it does not hold. Important: the code inside if/else is indented (4 spaces). int(...) turns the input into a number so you can compare it.

   nano /home/student/python/entscheidung.py:

   age = int(input())
   if age >= 18:
       print("adult")
   else:
       print("minor")

   Test with python3 /home/student/python/entscheidung.py and the inputs 17 and 18.

   Check: For 17 it prints minor, for 18 it prints adult. The checker tests exactly this boundary.

4. 4. A for loop

   Concept: for loop. A for loop repeats a block for each element of a sequence. range(1, n + 1) produces the numbers 1 to n.

   nano /home/student/python/schleife.py:

   n = int(input())
   for i in range(1, n + 1):
       print(i)

   Test with the input 3 — it prints 1, 2, 3 one below the other.

   Check: The script counts from 1 to the entered number, one number per line. The checker tests with 3 and with 6.

5. 5. Your own function

   Concept: function (def). A function bundles code under a name so you can reuse it. It takes parameters and hands back a result with return.

   nano /home/student/python/funktion.py:

   def square(number):
       return number * number
   
   x = int(input())
   print(square(x))

   Test with the input 4 — it prints 16.

   Check: funktion.py defines a function with def and a parameter, and the script prints the square of the entered number. The checker tests with 4 and 7.