c# - Loops using coroutines -

i have question coroutine behaviour in case of loops, see following code extract example done on unity c# script:

void start() {     startcoroutine(fsm()); }  ienumerator fsm() {     state="state1";     while (true) {         debug.log("state "+state);         yield return startcoroutine(state);     } }  ienumerator state1() {     while (true) {         if (statetransitioncond) {             state = "nextstate";             yield break;         }         yield return null;      } } 

the status machine works fine, while current status status1 (statetransitioncond==false), due yield return null inside loop of state1() routine, expecting loop inside fms() performs iteration generating debug log 'debug.log("state "+state);'.

in other words expecting lot of debug log (one each iteration of state1() routine, when status status1) in reality 1 execution performed while status status1.

so suppose miss yield functionality, there can explain me behaviour?

your issue stems fact code not break out of state1() method until statetransitioncond == true.

the method starting coroutine, fsm(), not returned until state1 finished. in other words, control flow not return calling method until coroutine complete. believe due fact yield-ing state1 inside fsm (yielding coroutine). obviously, "normal" methods not wait coroutine finish before continuing execution.

please see code sample below illustrative example:

using unityengine; using system.collections;  public class coroutinetest : monobehaviour {     // current fsm state     public string state = "";       void start()     {            startcoroutine(fsm());     }         ienumerator fsm()     {            state = "state1";          while (true)         {                debug.log("state: " + state);             // executeonce execute once before returning outer function             yield return startcoroutine(executeonce());              // executeindefinitely execute indefinitely until while() loop broken             // uncomment test             //yield return startcoroutine(executeindefinitely());         }        }         ienumerator executeonce()     {            debug.log("calling executeonce()");         yield return new waitforseconds(1f);     }         ienumerator executeindefinitely()     {            debug.log("calling executeindefinitely()");         while (true)         {                debug.log("inside executeindefinitely()");             yield return new waitforseconds(1f);         }        }    }