说明：  内存管理函数myalloc() ，myfree()和测试使用时遇到的全部情况如：请求内存时遇到的内存不足，和能满足请求的几种情况：1.空闲区刚好与请求区大小一样2.空闲区比请求区大，但余下的不能划划分分会一个分区3.空闲区比请求区大但余下的能划分为一个空闲区。释放内存时也有好多种情况如：1.已经释放了的内存，再次要求释放2.请求释放的内存不属于myalloc分给的内存区3.释放成功，但释放块没有与前
(Memory management functions myalloc () myfree () and all the circumstances encountered in test use, such as: insufficient memory request memory when encountered, and to meet the request of several circumstances: 1. Free zone is just the same as the request size free zone than requested area, but the rest of the division branch of a partition can not be designated three free zone request the District, but the rest can be divided into a free zone. Release memory when a good variety of circumstances such as: release memory once again demanded the release of 2. Request to release the memory does not belong to the myalloc points to the memory area. Release success, but the release of the block is not in front)