What are the rules on declaring integers?

pert · April 27, 2018, 5:46am

olf2012:
Like most of the tutorial pages on Arduino.cc you should not rely on the information given here. Some are outright wrong e.g. the part about "variable rollover" using a (signed) int as an example.

I have submitted recommendations for improvements to that page:

github.com/arduino/Arduino

Issues with "Variables" reference page

opened 05:42AM - 27 Apr 18 UTC

closed 11:40AM - 27 Apr 18 UTC

per1234

Component: Documentation

https://www.arduino.cc/en/Reference/VariableDeclaration Change: ``` int inp…utVariable1; int inputVariable2 = 0; // both are correct ``` To: ``` int inputVariable1; int inputVariable2 = 0; // both are correct ``` (Remove blank line from end of code block) Change: ``` int calibrationVal = 17; // declare calibrationVal and set initial value ``` To: ``` int calibrationVal = 17; // declare calibrationVal and set initial value ``` Notes: - Remove one space indent. - Remove blank line from end of code block --- Change: ``` int x; x = -32,768; x = x - 1; // x now contains 32,767 - rolls over in neg. direction x = 32,767; x = x + 1; // x now contains -32,768 - rolls over ``` To: ``` byte x; x = 0; x = x - 1; // x now contains 255 - rolls over in neg. direction x = 255; x = x + 1; // x now contains 0 - rolls over ``` Notes: - Use a type that will be a consistent size when using any official Arduino core (thanks Coding Badly). - Signed integer overflow is undefined behavior so it's not a good thing to use in an example. - Add missing semicolon. - Don't use decimal separators. - Standard 2 space indentation rather than weird 3 space indentation. --- Change: >Once variables have been declared, they are used by to: >Once variables have been declared, they **can be defined** by --- Change: ``` int lightSensVal; char currentLetter; unsigned long speedOfLight = 186000UL; char errorMessage = {"choose another option"}; // see string ``` to: ``` int lightSensVal = 1234; char currentLetter = 'a'; unsigned long speedOfLight = 186000UL; char errorMessage[] = "choose another option"; // see string ``` Notes: - Consistent, standard indentation. - These are supposed to be examples of variable definition, not declaration. So define them. - `errorMessage` is an array. - Standard string initialization syntax. - Trim trailing space --- Change: ``` if (inputVariable2 < 100) { inputVariable2 = 100; } delay(inputVariable2); ``` To: ``` if (inputVariable2 < 100) { inputVariable2 = 100; } delay(inputVariable2); ``` (All previous code that would need to be inside a function was indented so either this should be indented for consistency or else other indentation should be removed) --- Change: >and it uses the value of the variable as an input parameter to the delay() function (` delay(inputVariable2)` ) To: >and it uses the value of the variable as an input parameter to the delay() function ( `delay(inputVariable2)` ) (remove leading space from code tag) --- "Some variable types" section: Since a comment in the variable definition examples says "see string", add a link to https://www.arduino.cc/reference/en/language/variables/data-types/string/ --- What's the deal with this page? It appears to be a Language Reference page but it's not in the [Language Reference repository](https://github.com/arduino/reference-en).

I'm happy to add to that issue if anyone has any recommendations.

Any specific suggestions for improvements to the Arduino documentation are welcome. It's unfortunate that the quality isn't better to start with but I've found the Arduino team is very receptive to suggestions, even if it takes them a little while to implement them sometimes.

It's now possible to submit pull requests for change proposals directly to the repository that contains the content the Language Reference pages are generated from:

There is an edit link on every one of those pages.

Other documentation don't have that system so you need to submit an issue report with suggested improvements here:

The specific page in question seems like it might be an orphan which is not linked to from any other page on the website but it will still show up in Google searches so it still needs to either be of high quality or removed.

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What are the rules on declaring integers?

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