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Category Archives: Uncategorized
Extra Disk Space on Linux – For Free! :-)
Today, I held a class on file systems, during which I demonstrated how to create a mountable image file on Linux. After mounting the image, my students and I somehow got to wonder what would happen, if you copied or … Continue reading
Posted in Fun, Linux, Non-technical, Uncategorized
Tagged container, file systems, image, linux, mkfs, mount, weird stuff
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The Brilliant Concept of Standard Streams in Unix (1)
1. The basic idea of standard streams In the 1980s, almost every book or class on computer science here in Germany started with an explanation of the EVA-Prinzip, where E stood for Eingabe (Input), V for Verarbeitung (Processing), and A … Continue reading
How to use ancient Morse code to solve a modern problem
If you own a Raspberry Pi mini computer the following problem may sound familiar to you: You just connected your Rasperry Pi to a network with automatic DHCP. Now you need to find out what IP address has been assigned … Continue reading
Posted in c, Information Theory, Linux, Raspberry Pi, Uncategorized
Tagged c, dhcp, gpio, ip address, linux, morse code, programming, Raspberry Pi
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Let’s make the heap explode!
This blog entry is dedicated to those who teach computer science at high schools and vocational schools. In one of my Java programming classes, only few of the students showed up. It didn’t seem to make sense to continue with … Continue reading
Posted in Java, Linux, Programming Essentials, Uncategorized
Tagged efficiency, garbage collection, heap, java, memory, Object Oriented Programming
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Floating Point Representation
Back in the days when I was in middle school, I started to develop a strong preference for “nice” and “short” numbers, such as 0.1. One likely reason was that any math problem in school was designed to yield a … Continue reading
Posted in Bit-Twiddling, Math, Uncategorized
Tagged double, exponent, float, floating point, ieee754, mantissa
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Pointers and References – Part 4 (Hacker Stuff) ;)
Ok, guys … party’s over. Some of you have requested some more in-depth stuff on pointers, so here we go: Function Pointer Arrays. Depending on your previous programming experience, Function Pointer Arrays (FPA) may seem a bit nerdy to you. … Continue reading
Posted in Pointers, Programming Essentials, Uncategorized
Tagged array, function, function pointer array, pointer
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A Beginner’s Guide to Object Oriented Programming (2)
Long time no see. I hope you still remember my recent posting on object-oriented programming. Here is part two, which I hope you are interested in. Today, we are going to have a look at inheritance. If you do not … Continue reading
Posted in Programming Essentials, Uncategorized
Tagged inheritance, OOP, polymorphism
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Subroutines, Functions, Methods
Most, if not all, programming languages allow you to create subroutines, functions, or methods, all of which follow the same principle. You can think of them as black-boxes that contain source code to perform a specific task. For example, you … Continue reading
Posted in Programming Essentials, Uncategorized
Tagged c, function, method, parameter, return value, source code, subroutine, variable
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Swapping Variables
Many algorithms, including the world-famous Euclidean, require to swap the values of two variables. So you probably know the following principle. int x = 8; int y = 123; int tmp = x; x = y; y = tmp; However, … Continue reading
Posted in Bit-Twiddling, Information Theory, Uncategorized
Tagged bit-twiddling, c, logic, variable, xor
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