C 函数 strcpy and memcpy, strdup, memcmp,memset 库函数皆小写
void *memcpy(void *dst, const void *src, size_t n);//Ifcopyingtakesplacebetweenobjectsthatoverlap,thebehaviorisundefined因此标准库提供了地址重叠时的内存拷贝函数:memmove(),该函数把源字符串拷贝到临时buf里,然后再从临时buf里写到目的地址 strcpy and me