function writeString(STRING *strParam)
{
	wait(-1);
	str_cpy(strParam, "hey this works!");
}

...

STRING *szRet = str_create("#256");
str_cpy(szRet, ""); //Set to length 0
writeString(szRet);
while(str_len(szRet) == 0) wait(1);
error(szRet);