No matter what platform you're using, it's highly recommended to use Linux for GTK development in C. Even if you have Windows, use a Windows Subsystem for Linux. This link will guide you on how to enable it on your machine. Then, you should be able to access a Linux terminal of some sort if you don't have one already.
Install the GTK3 libraries:
sudo apt-get install libgtk-3-dev
Install the C compiler itself:
sudo apt-get install gcc
Install the Geany Text Editor:
sudo apt-get install geany
Compile command:
gcc `pkg-config --cflags gtk+-3.0` -o converter converter.c `pkg-config --libs gtk+-3.0` -lm
Execute command:
./converter
Allowed input:
decimal -> binary: less than or equal to 99998 decimal -> hex: less than or equal to 999999999
binary -> decimal: 20 bits or less binary -> hex: 20 bits or less
hex -> decimal: less than or equal to fffffff hex -> binary: less than or equal to ffff
Compile command:
gcc `pkg-config --cflags gtk+-3.0` -o calculator calculator.c `pkg-config --libs gtk+-3.0` -lm
Execute command:
./calculator
Allowed input:
Adding -> 16 bits each Subtracting -> only positive results allowed (top must be greater than bottom)
Additional enhancements to the calculator and converter are always welcome! Just try to follow the GitHub Flow guidelines while doing so.