Have you seen the “at” symbol twice with numbers in between? The double at symbols (@@) are known as chunk symbols and is part of the “Unified Format”. You can probably deduce it to some extent by looking at the graphics below: It basically tells you which lines have changed and the range or number… Read More »
Understanding linked lists is very important when learning C. Understand it, master it and be able to teach it. This link explains it very well. http://cslibrary.stanford.edu/103/LinkedListBasics.pdf The key is to get your hands dirty and not only write the code samples, but experiment and alter the values and play around with it. Here is a link… Read More »
Knowing a nice person is good, being nice, even better but in the computer world, there is this funky concept of “nice” which determines the scheduling priority of a process. The scope here is that you are doing some programming and you want to be able to control or set the priority. You can set… Read More »
If you have come across some code with reference to swab32 or bswap_32 and wondered how it works, here is the answer. swab32 will probably be a function that calls bswap_32 which will probably be a macro. The macro will probably be defined as: ( (((x) << 24) & 0xff000000u) | (((x) << 8) &… Read More »
This is all about endianness. That is, how the bits are arranged in memory. You can arrange these bits in memory 2 ways. In big endian or in little endian. Go to wikipedia for some background but esssentially big endian is the way the decimal system works and little endian is the reverse of this.… Read More »
In Ubuntu, this comes out of the box but in terminal on OSX a few extra steps are required to get this to work. It is a bit of a hassle figuring out what needs to be done, but once you know, it literally takes 10 seconds. Step 1: Download auto completion script: >> cd… Read More »
Step 1: Add Mongodb to your sources.list.d (for Ubuntu 14.04) This allows you to get the latest files from mongodb.org when you run sudo apt-get install echo “deb http://repo.mongodb.org/apt/ubuntu trusty/mongodb-org/3.0 multiverse” | sudo tee /etc/apt/sources.list.d/mongodb-org-3.0.list Step 2: Reload the local package database sudo apt-get update Step 3: Install MongoDB sudo apt-get install -y mongodb-org -y automatically… Read More »
Step 1: Stop the service sudo service mongod stop Step 2: Remove packages sudo apt-get purge mongodb-org* Step 3: Remove data directories sudo rm -r /var/log/mongodb sudo rm -r /var/lib/mongodb -r means recursive Reference: https://docs.mongodb.org/v3.0/tutorial/install-mongodb-on-ubuntu/
A simple concept in the C language is the evaluation of a boolean expression with an if statement. But what if the condition is not a typical relational or boolean expression? In C, it is possible to write: if (x){ // if x is true or great than zero printf(“x is true/has a value/great than… Read More »
Came across this detailed paper “What Every Programmer Should Know About Memory” by Ulrich Drepper dated 21 November 2007. (http://www.akkadia.org/drepper/cpumemory.pdf) It is a long read but provides a wealth of background which explains some good fundamental concepts that are still valid today. Another article, http://marek.vavrusa.com/c/memory/2015/02/20/memory/ puts another “practical” spin on the original paper and is also… Read More »