笔试题：写出memmove原型

memcpy与memmove都是实现从src拷贝n个字符串到dest。

区别：memmove能够处理src与dest区域重叠情况。

 

void *memmove(void *dest,const void *src, size_t n){ char *dmp; const char *smp; if(dest <= src) { dmp = (char *)dest; smp = (const char *)src; while(n--) *dmp++ = *smp++; } else { dmp = (char *)(dest + n); smp = (const char *)(src + n); while(n--) *--dmp = *--smp; } return dest;} 

void *memcpy(void *dest, const void *source, size_t count) { assert((NULL != dest) && (NULL != source)); char *tmp_dest = (char *)dest; char *tmp_source = (char *)source; while(count --)//不对是否存在重叠区域进行判断 *tmp_dest ++ = *tmp_source ++; return dest; }