String object strange behaviour

[danielhuber 2]

I am running an MSP-EXP430G2 Lauchpad with an MSP430G2553 on Windows 7.

 

The following code:

============================

#include <IRremote.h>

String st;

 

void setup()

{

     Serial.begin(9600);

     st=String();

}

 

void loop()

{

   st=st+'2';

   Serial.println(st);  

   delay(200); 

}

===============

produces following output:

2

22

222

2222

22222

222222

2222222

22222222

222222222

2222222222

22222222222

222222222222

2222222222222

22222222222222

222222222222222

2222222222222222

22222222222222222

222222222222222222

2222222222222222222

 

2

22

222

2222

.....

After a string length of 19 the string is cleared.  Why?

When exactly this happens depends also on additional code.

With a MPU with lesser RAM I would guess that the RAM overflows, but 0.5kB of the MSP430G2553 should be large enough.

Has anybody an explanation?

cheers, Daniel

[roadrunner84 466]

Because String does use dynamic memory, which your MSP430 does barely handle. Either declare your string with a decent size, or use plain c-strings.

String st(100, '\0');

or

char st[100] = "";