gistfile1.txt

#define MYBUFFER_SIZE 64
char *mybuffer;

void setup()
{
	SerialUSB.begin();
	
	mybuffer = malloc(MYBUFFER_SIZE); // Allocate a MYBUFFER_SIZE-byte buffer for global use.
}

void loop()
{
	// strGenMethod1 will allocate space for a 16-byte string, fill it with text and return a pointer to it.
	char *method1 = strGenMethod1();
	if(method1 != NULL) // malloc can return NULL if it's unable to allocate the required memory.
	{
		SerialUSB.println(method1);
		free(method1); // If  you don't free the memory, once loop() finishes you'll have a 16-byte memory leak.
		// If you don't free the memory, on the ~1281st loop malloc will fail because all 20kB of RAM were allocated,
		//    and the MCU still thinks they're in use.
	}
	
	// strGenMethod2 will zero-out the entire buffer, and wrote your string to it.
	strGenMethod2(mybuffer, MYBUFFER_SIZE);
	SerialUSB.println(mybuffer);
	// Because it's a global buffer that is re-used, you don't need to worry about releasing the memory back.
	// This is the generally preferred method of getting the job done.	

	SerialUSB.println("This is OK!!");
}

char *strGenMethod1()
{
	char *buff = malloc(16);
	if(buff == NULL) return NULL;
	
	sprintf(buff, "This is Wrong!!");
	return buff;
}

void strGenMethod2(char *buff, int n)
{
	// Using memset on the entire length of the buffer is expensive and time consuming.
	//    You may not need to do it, since "a string" is always \0 terminated.
	memset(buff, '0', n);
	sprintf(buff, "This is wrong!!");
}