malloc and free are two functions in C language for dynamic memory allocation and release. The malloc function is used to allocate a memory space of a specified size on the heap, and the free function is used to release the previously allocated memory space so that it can be reused.
The relationship between malloc and free is that the memory space allocated by malloc must be released by the free function after use, otherwise it will cause memory leaks. At the same time, the free function can only release the memory space allocated by the malloc function before, otherwise it will cause the program to crash or other unpredictable errors. Therefore, when using malloc and free, you need to pay attention to the order of memory allocation and release, as well as the correctness and legality of the memory space.