Python recap: Difference between revisions

Revision as of 15:22, 25 August 2025

Required course material for the lesson

Powerpoint: Python Recap
Resource: Example code - Basics

Subjects covered

This is a superficial recap on Python variables, assignment, some operators (+-*/.), conditional statements with if, looping using for and while. built-in functions like print, len, range, input and type casting functions int, float and str. Well-known list and string methods, like split or strip. Various standard libraries like os, sys, and math.
It is expected that students know python to this level when starting the course.

Advice

Data and program code are separate entities, which go together. However, data can not be executed as code, and code is not typically thought of as data.
You can assume that the user is well-behaved enough to only input numbers, when numbers are required.
You can not assume that the user will not input numbers which in some way will give rise to a wrong/faulty/misbehaving calculation.

Exercises to be handed in

A new function to be used in these exercises are the input function which gets a string as input from the keyboard.

First a tricky exercise - read carefully and think what this means. Make a program that asks for number, and then continues asking for numbers as long as you input numbers that are greater or equal to all previous numbers (not the sum of previous numbers). Hint: use a list and you fail.
You have previously calculated the factorial of a number - this is somewhat similar.Ask for an integer and calculate the sum from 0 up/down to the integer. An example: If you input 5 then calculate 5 + 4 + 3 + 2 + 1 (+ 0) = 15. If input is -4 then calculate -4 + -3 + -2 + -1 (+ 0) = -10.

Exercises for extra practice

Ask for a word 4 times. Display all the words afterwards, one word per line.
Ask for a word 7 times. Display all the words afterwards on one line.
In a loop ask for words. Add them together in the order given so they form a (maybe meaningless) sentence. When you do not enter anything (i.e. just hit the <enter> key), you stop the loop and display the sentence.
In a loop ask for numbers using the input function. Add the numbers together as the are entered. End the loop when you write STOP instead of a number. Display the sum of the numbers.
Hint: Check for STOP before you try to typecast (convert) the number.
Continue to ask for numbers until you don't enter anything. Then display all the numbers and their sum. Example: The numbers 1, 2 & 3 is entered and "1 + 2 + 3 = 6" is displayed. Hint: You need use the numbers both as string type and number type.

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 == Exercises to be handed in ==
-# The very first exercise is to write some syntactically wrong python (that should not be hard). The purpose is to show you how a ''stack trace'' looks. You should learn how to read this confusing text, at least to the point where you can understand what the error in your program is.
+A new function to be used in these exercises are the ''input'' function which gets a string as input from the keyboard.
-# Write numbers 1 to 10 to the screen one number per line. Use a loop.
+# First a tricky exercise - read carefully and think what this means. Make a program that asks for number, and then continues asking for numbers as long as you input numbers that are greater or equal to all previous numbers (not the sum of previous numbers). Hint: use a list and you fail.
-# Write 'Hello World' 10 times using a loop. One Hello per line.
+# You have previously calculated the factorial of a number - this is somewhat similar.Ask for an integer and calculate the sum from 0 up/down to the integer. An example: If you input 5 then calculate 5 + 4 + 3 + 2 + 1 (+ 0) = 15. If input is -4 then calculate -4 + -3 + -2 + -1 (+ 0) = -10.
-# Make a program ask for a name, and then write a greeting using that name. However, if it is your name you give as input the greeting should be extra nice.
-# Make a program that ask for two numbers (one at a time) and then prints them and their sum.
-# Ask for two numbers and ask what operation to perform on them (+, - , *, /) and display the numbers and the result.
-# Ask for two integers and print them and all integers between them. It is not necessary to perform input control - just assume that the user is well-behaved and inputs integers.
-# Now make the same program work even if you switch the input numbers, so it does not matter if you input the smallest number first or last.
-# This needs to be read carefully: Make a program that asks for number, and then continues asking for numbers as long as you input numbers that are greater or equal to all previous numbers (not the sum of previous numbers).
-# Ask for a positive integer and calculate the factorial (n!) of that number. Display the result. If input is negative, display an error message.
-# If you solved the previous one then this should be relatively easy. Ask for an integer and calculate the sum from 0 up/down to the integer. An example: If you input 5 then calculate 5 + 4 + 3 + 2 + 1 (+ 0) = 15. If input is -4 then calculate -4 + -3 + -2 + -1 (+ 0) = -10.
 == Exercises for extra practice ==