memove和memcpy源码实现

最新推荐文章于 2025-09-11 11:09:21 发布

原创最新推荐文章于 2025-09-11 11:09:21 发布 · 538 阅读

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CC 4.0 BY-SA版权

本文详细解析了C语言中memcpy和memmove函数的工作原理及使用场景。针对内存复制时源和目的地址是否重叠的情况，提供了不同的实现方式，确保数据正确高效地复制。

void* memcpy(void* dest, void* source, size_t count)
{
          void* ret = dest;
          //copy from lower address to higher address
          while (count--)
                  *dest++ = *source++;
           return ret;
}

 
void* memmove(void* dest, void* source, size_t count)
{

       void* ret = dest;
       if (dest <= source || dest >= (source + count))
       {
          //Non-Overlapping Buffers
          //copy from lower addresses to higher addresses
         while (count --)
               *dest++ = *source++;
       }
       else
       {

        //Overlapping Buffers
        //copy from higher addresses to lower addresses 内存重叠的情况
         dest += count - 1;
         source += count - 1;
         while (count--)
                *dest-- = *source--;
        }
        return ret;
}