How do you reset a int ?

Projects Interfacing w/ Software on the Computer
1

Hi
I want to reset a int to nothing ? how do I do this ?

something like this !, but this does not work because I´m not allowed to use null;
int x;

void draw(){
int x = 5;
int x = null;
}

2 
int x;  // Creates a global variable called x containing 0

void draw(){
int x = 5;  // Creates a local variable called x containing 5
x = 0;       //  Changes the local variable x to contain 0
}  // End of function.  Local variable stops existing
3 
void draw(){

Makes it look like Processing code not Arduino code.

4

something like this !, but this does not work because I´m not allowed to use null;
int x;

void draw(){
int x = 5;
int x = null;
}

This would give you 3 variables with the same name. Why would you want to do that?

I want to reset a int to nothing ?

Why? No int ever is set to nothing. What are you trying to accomplish?

5

An int can't be "nothing", it's always a number of some kind.

Depending on it's valid range in the program it's common to set it to -1 to indicate that it's not valid, an error or whatever.

If all values are valid in your code then you need a separate flag to indicate that the int is not currently containing valid data.

As PaulS said, what do you really want to do?

Rob

6

You can create an object wrapping an int, or you can use a pointer to an int.
Or -simpler- have an additional boolean saying undefined/defined.

Usually, the "special value" method indicating it's undefined, is easiest.
It just depends on the use case, but usually, there are some invalid states, even in a small signed 16 bit integer.
Take -32768 = 0x8000, if 0 and -1 are both "not null".

use it like this:

#define INVALID 0x8000
...
int x = INVALID;
...
if (x == INVALID)
x = initializeIt();