memcpy/memset

1.memcpy

memcpy是内存拷贝函数，原型为：

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

将n个字节的内存从src拷贝到dest

实现代码：

void *memcpy(void *dest, const void *src, size_t n){assert(dest != NULL && src != NULL);char *d = (char*)dest;const char *s = (char*)src;for(size_t i = 0; i < n; i++)*d++ = *s++;return dest;}

2.memset

memset 是将指针s指向的前n个字节全部置为ASCⅡ值为ch，返回值为指向s的指针，函数原型为

void *memset(void *s, int ch, size_t n);

void *memset(void *s, int ch, size_t n){assert(s != NULL);const unsigned char uc = ch;char *temp = (char*)s;for(size_t i = 0; i < n; i++)*(temp+i) = uc;return s;}