编写动态存储分配的一部分

代码说明：

Memory Allocation in C-write part of a dynamic storage allocation package. The package provides three function calls: void initalloc(), to initialize the data structures involved char* alloc(int n), which returns a pointer to a block of n chars when called and void freef(char* p), which frees the block of n chars earlier given to the data structure so that it can be given out to another.