boolean (8 bit) - simple logical true/false, Arduino does not use single bits for bool
byte (8 bit) - unsigned number from 0 to 255
char (8 bit) - signed number from -128 to 127. The compiler will attempt to interpret this data type as a character in some circumstances, which may yield unexpected results
unsigned char (8 bit) - same as 'byte'; if this is what you're after, you should use 'byte' instead, for reasons of clarity
word (16 bit) - unsigned number from 0 to 65535
unsigned int (16 bit)- the same as 'word'. Use 'word' instead for clarity and brevity
int (16 bit) - signed number from -32768 to 32767. This is most commonly what you see used for general purpose variables in Arduino example code provided with the IDE
unsigned long (32 bit) - unsigned number from 0 to 4,294,967,295. The most common usage of this is to store the result of the millis() function, which returns the number of milliseconds the current code has been running
long (32 bit) - signed number from -2,147,483,648 to 2,147,483,647
float (32 bit) - signed number from -3.4028235E38 to 3.4028235E38. Floating point on the Arduino is not native; the compiler has to jump through hoops to make it work. If you can avoid it, you should. We'll touch on this later. Sparkfun.
You select the 'type' best suited for your variables.
ex:
your variable does not change and it defines a pin on the Arduino. const byte limitSwitchPin = 34;
since an analog variable can be 0 to 1023, a byte will not do, you can select 'int'. int temperature;
if your variable needs to be within -64 to +64 a 'char' will do nicely. char joystick;
if your variable is used for ASCII then you need type 'char', char myText[] = {"Raspberry Pie Smells"};
if your variable enables some code then boolean can be used. boolean enableFlag = false;
millis() returns the time in ms since rebooting, unsigned long currentTime = millis();
etc.
Believe it or not, I will make sure I read and evaluate all that information, I am really excited to start learning from the beginning this technology.
one of the best books i read on how to write good programs was The Elements of Programming Style by kernighan and plauger and only about a 1/4" thick. kernighan later wrote The C Programming Language. progamming style showed textbook programs, identified and fixed their flaws and how to make them better
kernighan edited C++ Prgramming Style by cargill which similarly shows what look like good C++ programs, discusses their flaws and how to write them properly.
I have manipulated 2 or 3 codes for some personal projects. I consider they were just few modifications such as commenting out some lines, changing I/O pins to match my Arduino board, installing libraries.
Not much of a good foundation of 'C' itself. I'd like to be able to write my own code, at least a 10 lines code, that's something wouldn't be possible right now,
It really depends on how you like to learn and what your goal is. If you find a C or C++ tutorial and work through it until you can use arrays and write functions, that'll be sufficient to get started on coding for Arduino.
I rather suspect that most people don't bother with that and learn by hacking existing code and getting help here when they get stuck.
If you work through all the material that larryd linked, I expect you will be the one dispensing advice.
It may help to have a project in mind to guide you in choosing what to learn first.
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