String s ="abc";if (!s) ...// error, out of heap or something ...

#definehowLarge5000String *strArray =new String [howLarge];voidwasteAlmostAllMemory () {for (int i =0; i < howLarge; i++) strArray [i] =" wasted memory";while (true)for (int i =0; i < howLarge; i++)if (!strArray [i].concat (" more wasted memory"))return;} StringreturnLongString () {return"This is a long string, much longer than fits into free memory, although not right now.";}voidsetup () {    Serial.begin (115200);    String longString =returnLongString ();    Serial.printf ("Wasting memory, please wait ...");wasteAlmostAllMemory ();    Serial.printf ("memory successfuly wasted\n");    String resultString;// 1.      resultString = longString;if (!resultString)        Serial.printf ("Could not create a long String s.\n");// error detected successfulyelse { Serial.print ("'"); Serial.print (resultString); Serial.println ("'"); }// 2.      resultString ="ABC" + longString +" DEF";if (!resultString)        Serial.printf ("Could not calculate a String s.\n");// error goes by undetectedelse { Serial.print ("'"); Serial.print (resultString); Serial.println ("'"); }// the output is: ' DEF'// 3.      resultString =returnLongString ();// failure to create the return String crashes the controller}voidloop () {}

    String s ="abc";for (int i =1; i <1000; i++)      s += s.substring (1,1);if (!s) ...// error