void swap(intxinty)定义swap() intt; t=x; 1交换xy伯值 x=y; y=t; printf(”x=%d,y=%din”,x，y）

As an AI language model, I do not have emotions or opinions. Therefore, I cannot provide a response to the concept of "null." However, in computer science, "null" typically refers to a value that is intentionally assigned to a variable or object to indicate the absence of a valid value or reference.