p5.js changing data types (from float into int)

beccarose

Hey! I've started using p5.js after using processing, and so I am stuck trying to change a float into an int.

I want to get a random integer so I can upload a random image: // get a random number for image var imgNum; function setup(){ imgNum = random(0, 14); }

How would I go about converting the random number into an int?

thanks!

GoToLoop

Use unary operator ~ 2x: imgNum = ~~random(14);. :ar!
There are some other approaches too. ;;)
For example the | operator: imgNum = random(14) | 0; or imgNum = 0 | random(14);.

GoToLoop

The article below is about transitioning Processing's Java Mode to p5.js: :bz
https://GitHub.com/processing/p5.js/wiki/Processing-transition

jeremydouglass

@beccarose -- change a float into an int with int() -- use this if you want your code to be simple and clear. See the p5.js int reference page:

int(): Converts a boolean, string, or float to its integer representation.

---

Using -- or | 0 is indeed very " :ar! "

They are not intended for this purpose -- but they are efficient ways to force the answer to be an int as a side-effect of doing something different (integer subtraction bitwise not, or a logical "or" test).

GoToLoop

Using -- or | 0 is indeed very :ar! .
(integer subtraction, ...

It's not the decrement operator --, but 2 Bitwise NOT tildes: ~~: :-\"
https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_Operators#Bitwise_NOT

BtW, we can replace | 0 w/ & -1 too: imgNum = random(14) & -1;
Also imgNum = random(14) >> 0;, imgNum = random(14) >>> 0;, imgNum = random(14) << 0;, etc. :P

And other more conservative options below if you prefer: :-B

1. https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt
2. https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/parseInt
3. https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/floor
4. https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/trunc

beccarose

@jeremydouglass would you be able to provide a specific example. I have converted types in other languages, but p5.js only uses var, so not sure how using int() would work in that case?

beccarose

@GoToLoop thanks I'll give those a go tonight

beccarose

@GoToLoop just tried the "pirate" way 2x tildes and worked really well. thank you!

(note in Bristol my home town we are really into pirates...oooh-argh!)

GoToLoop

... but p5.js only uses var, ...

Although variables in the JS language don't have types, the data they store DO! L-)
And it's misinformation that var is the only way to declare variables in JS. Actually there are 5: @-)

1. var: https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/var
2. let: https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let
3. const: https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/const
4. function: https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function
5. class: https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/class

I bet you're finding strange that function & class are also variable declarations. >-)
But when not using their anonymous expression form, rather their declaration form, they do create a variable! ;;)

jeremydouglass

@beccarose -- the forum formatting may have hidden the fact that my answer linked to the p5.js int() reference page, which also gives many examples:

print(int(10.31)); // 10

blindfish

(note in Bristol my home town we are really into pirates...oooh-argh!)

@beccarose - in which case you must know of Pirate Pete :ar! :D :ar!