模拟实现memcpy 与 memmove

模拟实现memcpy 与 memmove

1.str系列的函数只能处理字符串——>必须带有'\0'
2.memcpy内存处理函数：不涉及'\0',需要包含头文件 string.h
3.source的内存不能超过destination的内存大小
4.存在缓冲区的重合问题，要保证destination指向有效的区域：可以用从右往左拷贝的方法
//memmove可以解决mencoy的缓冲区重合的问题

 #include<stdio.h>
 #include<assert.h>
 void Memcpy(void* destination, const void* source, size_t num)
 {
  assert(destination != );
  assert(source != );
  char* dest = (char*)destination;
  char* sour = (char*)source;
  for (size_t i = ; i < num; i++)
  {
   dest[i] = sour[i];
  }
  return destination;
 }
 void Memmove(void* destination, const char* source, size_t num)
 {
  assert(destination != );
  assert(source != );
  char* dest = (char*)destination;
  char* sour = (char*)source;
  //两种情况：
  if (sour<dest&&sour + num>dest)
  {
   //1.缓冲区重合就从后往前拷贝
   for (int i = num - ; i >= ; --i)
   {
    dest[i] = source[i];
   }
  }
  else
  {
   //2.缓冲区没重合，代码和memcpy一样
   Memcpy(destination, source, num);
  }
 }
 int main()
 {
  int arr1[] = { ,,, };
  int arr2[] = {  };
  Memcpy(arr2, arr1, sizeof(arr1));
  for (int i = ; i < sizeof(arr1) / sizeof(int); i++)
  {
   printf("%d",arr2[i]);
  }
  return ;
 }