Pass INT from class back to global

Programming Questions

alanhelton

Pass INT from class back to global

in Programming Questions • 1 year ago

I am having trouble passing a variable from a function inside of a class back out to its public variable. readRX is initialized 0, and then gets changed to 5 within the class. however, it does not change the public variable, readRX to 5.

If you rin the program, it will successfully print r as 5, but readRX will always read 0.

On a related note, (sorry the example is not here) passing a float[] into the class, not an int, will change the global float[] variable.

How do I pass a variable from a class back into the global environment?

Class nmz;
int readRX = 0;
void setup()
{
size(1110, 256);
}
void draw()
{
nmz = new Class(readRX);
nmz.RX();
println(readRX);
}
class Class{
int r;
Class (int readRX) {
r = readRX;
}
void RX(){
r = 5;
println(r);
}
}

Replies(4)

thomas.di..

Re: Pass INT from class back to global

1 year ago

arrays/objects given as parameters are passed by reference, while primitive datatypes (int, float, etc) are passed by value (they are copied).

so you have two options, either you pass an array (int[] with size of 1 ) as a "buffer", or the method RX has int as return type:

int void RX(){
r = 5;
println(r);
return r;
}

alanhelton

Re: Pass INT from class back to global

1 year ago

What a strange thing!

I tried returning the value, but got:

Void methods cannot return a value

So an array of [1] did the trick.

Thanks!

thomas.di..

Re: Pass INT from class back to global

1 year ago

sorry, my mistake:

int RX(){ //instead of "int void RX"
r = 5;
println(r);
return r;
}

alanhelton

Re: Pass INT from class back to global

1 year ago

Should have known this. These are my first classes. I guess I was caught up in them. Thank you!