Below you’ll find the code of a simple server-client program in C using UDP sockets for the transmission. Basically the client sends a message to the server, the server converts the message to uppercase and returns it to the client. If you want to see a simpler program first check this client-server program that only […]
Below you’ll find an example of a client-server application that uses sockets programming in C. Basically the server listens for connection requests, and whatever message the client sends the server converts it to uppercase and sends it back. You could see this as the server providing a service of converting strings to uppercase. The server […]
Below you’ll find an example of a very simple client-server program in C. Basically the client connects to the server, the server sends the message “Hello World”, and the client prints the received message. Keep in mind that I am configuring the settings manually. If you want your code to be IPV4-IPV6 agnostic, IP agnostic […]
The program below illustrates functions and methods you can use to investigate the allocated (virtual) memory of your process. For instance, you can get and print the limit of your data section, guess the limit of your stack and so on. One curious thing you’ll notice is that small mallocs appear to allocate memory inside […]
I am working on a project where I’ll need to do some animations straight in the terminal with ASCII. I believe you can do that in a sophisticated way using the NCurses library, but as usual I want first to see what I can do with bare C functions and syscalls. I discovered that most […]
Below you’ll find a simple C program that creates 5 worker threads. The threads then wait until the main thread gives them a signal to start the work. I employ different primitives to make this synchronization happen. Note: Remember that you need to compile this programs with the -pthread GCC option. Note 2: When you […]
If you never use GDB (The GNU Project Debugger), well, you should! It’s easy to underestimate its usefulness when debugging programs. Below you’ll find some very basic commands that will get you started: First of all you need to compile/assemble your program with the -g flag, which will include in the executable the necessary code […]
This might not be the most efficient way, but it’s certainly one of the easiest. You simply need to convert both integers into strings using sprintf, concatenate those using strcat, and then reverse the combined string to an integer using the atoi function. int concat(int x, int y){ char str1[20]; char str2[20]; sprintf(str1,"%d",x); sprintf(str2,"%d",y); strcat(str1,str2); […]
Huffman Coding (link to Wikipedia) is a compression algorithm used for loss-less data compression. Here’s the basic idea: each ASCII character is usually represented with 8 bits, but if we had a text filed composed of only the lowercase a-z letters we could represent each character with only 5 bits (i.e., 2^5 = 32, which […]
Problem 54 on ProjectEuler.net was an interesting one. Instead of the usual math puzzle it had a more practical topic: Poker. You basically need to evaluate the hands of two players for 1000 rounds, and then determine how many rounds rounds player one wins. The hand evaluator I built was quite naive and used a […]