Shulou(Shulou.com)05/31 Report--

This article mainly introduces the relevant knowledge of "how to allocate dynamic memory in C language". The editor shows you the operation process through an actual case, which is simple, fast and practical. I hope this article "how to allocate dynamic memory in C language" can help you solve the problem.

When we write a program, we need to define variables such as "unsignedchar a [100];". When this statement is executed, the compiler allocates 100 bytes of memory to the array a. However, as we have briefly mentioned before, the array definition statement "unsignedchar a [100];" is itself a variable type of Auto type. As we said earlier, variables of type Auto are automatically stored in the "stack" space by the compiler. This approach has a very inconvenient place, once I need to store more than 100-length data on array a, then the whole program will have a memory overflow. If the array is defined very large at the beginning, but the vast majority of the actual data does not need to be so large in practical use, it will also lead to a waste of storage space. Is there a way to make the storage space of this array change at will? The answer is obviously yes, which is to make memory request dynamic. The C language provides two library functions, malloc and free, to perform dynamic memory allocation and release, respectively. Note that in C language, after the use of memory applied for with malloc is completed, it must be released manually, otherwise the memory will be exhausted and the program will stop running. Malloc and free maintain an available memory pool, which we previously called the "heap" area. When a program needs a suitable piece of memory, it uses the malloc function to apply, that is, to take out a suitable piece of memory and return a pointer to it. It is important to note that after this memory is taken out, it is not initialized, so we need to initialize it manually. Then, when the program no longer wants to use this piece of memory, use the free function to return it to the memory pool. Both functions are declared in the lib.h > header file, and their prototypes are:

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