// Make sure expr1,expr2 is at least the size of buff !
char partition(char *buff, char *expr1, char* expr2)
{
	 // 0 is returned if the sign wasn't found
	static char sign = 0;
	// Always validate pointers before using them
        if(buff == 0 || expr1 == 0 || expr2 == 0)
		return sign;
	char current = *buf;
	// End of the null terminated buffer
	if(current == 0)
	 	return sign;
	// We already found the sign, we can set the value in the 2nd expression
	if(sign != 0)
	{
		*expr2 = current;
		return partition(buff++, expr1, expr2++);
	}
	else
	{
		if(current ='+'  || .... )// test all signs
		{
		   sign = current;
	           return partition(buff++, expr1, expr2);
		}

		*expr1 = current;
		return partition(buff++, expr1++, expr2);		
	}
	
	
}