If that is called from within draw(), you gotta be aware that by default, draw() is invoked 60 times a second!
So, for each second, button1() is also called 60 times.

And if those calls are made when button1time == 0, you're gonna get 60 true conditions during that second.

better work with  
int a1 = millis() % 10000;
because second is referring to the actual time, so it goes from 0 to 59 and then to 0 again.....
millis counts on and on....


Greetings, Chrisir

If you need an answer, please send me a personal message since this forum doesn't notify.

Thanks both of you, I tried implementing millis Chrisirs response but in fact couldn't get it to + to the counter at all.

this does one thing every 10 secs: make the rect longer.

It is not based on % but on a timer.

1. //
2. int len=10;
3. int last;
4. //
5. // ---------------------------------------------------------------
6. //
7. void setup()
8. {
9.   // init
10.   size(800, 600);
11.   last=millis();
12. } // func
13. //
14. //
15. void draw()
16. {
17.   background(255);
18.   if (millis() - 10000 >= last) {
19.     len+=10;
20.     last=millis();
21.   }
22.   rect(10, 10, len, 10);
23. } // func
24. //
25. // =====================================================================

Thankyou! This has worked perfectly, absolute lifesaver! :)