#include     //printf

 #include     //ssert

 #include     //malloc

 #include     //strlen

 char * sstrcpy(char * strdst, char * strsrc)

 {

     char *dst = strdst;

     assert(strdst!=NULL && strsrc!=NULL);

     while((*strdst++ = *strsrc++)!= '\0')

         NULL;

     return dst; //实现链式表达式

 }

 //int num = strlen(strcpy(strdst,"hello world"));

 int main(void)

 {

     int num;

     char *strdst = (char *)malloc(sizeof(char)*);

     if(strdst == NULL)

         return (-);

     num = strlen(sstrcpy(strdst,"hello world"));

     printf("%d\n", num);

     return ;

 }