模拟函数memmove

#include <stdio.h>//怎么实现是从前往后拷贝，还是从后往前拷贝 #include <assert.h> //拷贝函数，核心是可以处理内存重叠的情况 //定义 void *my_memmove(void *dest,const void *source,size_t n) { //准备工作 // assert(dest != NULL); // assert(source != NULL); assert(dest != NULL && source != NULL); void *result = dest; //强转 char *p_dest = (char*)dest; const char *p_source = (const char*)source; //判断内存重叠，选择复制方向 if(p_dest <= p_source) { //正向 for(size_t i = 0;i < n;i++) { p_dest[i] = p_source[i]; } }else { for(size_t i = n-1;i != (size_t)-1;i--) { p_dest[i] = p_source[i]; } } return result; } int main() { // char a = "a b c d e f"; char b[]= "a b c d e f g v"; my_memmove(b +1,b,4); printf("%s",b); return 0; }

指针的强化运用，了解了size_t（-1）无符号。0xFFFFFFFF