IOS--DAY03---Memory allocation dynamic RAM allocation

Memory: Divided into five regions

• The stack area-----------system allocations and reclaims memory. The variables created in the function body exist in the stack area
• Heap areas are------------allocated and recycled by users, and if a user forgets to recycle, the heap memory is reclaimed by the system if the memory is not sufficient and the program exits
• Constant area-------------The area of memory used to hold constants
• Static area-------------variables defined in the function body, the system opens up space, the program has been in operation for a long time, until the program exits, the system is recycled
• Code Area----------------storing code compilation results

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malloc function

void *malloc (unsigned int size);

The malloc function allocates a size contiguous memory space to the system but does not clear the allocated space by 0

Free ();//Release memory

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void *calloc (unsigned n,unsigned size);

Allocate n sizes of size space

Unlike malloc, the memory space requested by Calloc is initialized to 0;

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void *realloc (void *p, unsigned newSize);

Re-allocating memory at new length

All three of these are released using free

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Memory manipulation functions

void *memset (void *s, int c, size_t N);

memset (p,0,sizeof (Student));

s begins, all bytes of length n are assigned C;

Usually used for clear structure or array data

void *memcpy (void *dest,const void *source,size_t n);

Copy n bytes from source to Dest

int memcmp (const void *buf1,const void *buf2,unsigned int count);

The above memory manipulation functions can be used for heap memory pages that can be used for stack memory

IOS--DAY03---Memory allocation dynamic RAM allocation