C言語:深いコピーVS浅いコピー配列VSポインタ

#include <stdio.h>

struct student{
       char *name1;
       char name2[20];
}stu;

int main()
{
    struct student *p;
    p = &stu;
    //strcpy((*p).name1,"first");//     ，    ，        。
    strcpy((*p).name2,"second");  //    ：          
    printf("name1 = %s \t name2 = %s
",(*p).name1,(*p).name2);
    
    p->name1 = "third";   //    ，        
    printf("name1 = %s \t name2 = %s
",(*p).name1,(*p).name2);
    //p->name2 = "fourth";  //    ： incompatible types in assignment of `const char[7]' to `char[20]' 
    char tp[20]="fifth";  
    //p->name2 = tp;  //    ：ISO C++ forbids assignment of arrays 
    //            
    strcpy((*p).name2,tp);
    p->name1 = tp;
    tp[0]='F';//  tp     
    printf("name1 = %s \t name2 = %s
",(*p).name1,(*p).name2); //          ，     
    
    //            
    printf("sizeof(char *name) = %d
sizeof(char name[20]) = %d
", sizeof(p->name1), sizeof(p->name2)); // 32    4 20 
    system("PAUSE");
    return 0;
}

name1 = (null)   name2 = second
name1 = third    name2 = second
name1 = Fifth    name2 = fifth
sizeof(char *name) = 4
sizeof(char name[20]) = 20