Advice: How to exchange values between the loops?

[Lech Wiecierzynski]

the program crash when i try something like this:

float val;

void loop(){
...
output = "value is;" + String(val);

void loop2(){

val=doSometingWhatCoastALotOfTime();

[Mikael Patel]

Check that there is enough stack and remember that yield() or delay() must be called to pass control between the tasks.

BW: Please add test code that I can use. That is not easy to understand or even give advice on. Also add version of Arduino and board type.