Arrays 我想在void函数的结构数组中添加信息,但我想我不';不要正确使用指针
所以我有这些结构,这样我的信息就可以存储了Arrays 我想在void函数的结构数组中添加信息,但我想我不';不要正确使用指针,arrays,c,pointers,dynamic,structure,Arrays,C,Pointers,Dynamic,Structure,所以我有这些结构,这样我的信息就可以存储了 typedef struct date { int day, month, year; } date; typedef struct director_info { char *director_surname, *director_name; } director_info; typedef struct movie { int id; char *title; director_info *director;
typedef struct date {
int day, month, year;
} date;
typedef struct director_info {
char *director_surname, *director_name;
} director_info;
typedef struct movie {
int id;
char *title;
director_info *director;
date *release_date;
} movie;
我有这个功能是为了添加新的信息,但是在虚空中所做的改变不会改变主要结构。。。有什么想法吗
void addMovie(movie *movies, int n)
{
int len;
char tmptitle[MAXN],tmpsur[MAXN],tmpname[MAXN];
date tmpdt ={.day=0};
date *newdate;
char stringToWrite[80];
movies[n].id=movies[n-1].id+1;// dinw id sthn kainouria ekxwrish
movies = (movie *) malloc(sizeof(movie));
printf("Enter title:");
scanf("%s", &tmptitle);
len=strlen(tmptitle);
movies[n].title = malloc (len + 1);
memcpy (movies[n].title,tmptitle, len + 1);
director_info *newinfo;
//newinfo = malloc (sizeof *newinfo);
newinfo = (director_info*) malloc(sizeof(director_info));
newdate = (date*) malloc(sizeof(date));
printf("Enter the surname of the director:");
scanf("%s", &tmpsur);
len = strlen (tmpsur);
newinfo->director_surname = malloc (len + 1);
memcpy (newinfo->director_surname, tmpsur,len + 1);
memcpy (movies[n].director->director_surname,tmpsur, len + 1);
printf("Enter the name of the director:");
scanf("%s", &tmpname);
len= strlen (tmpname);
free(newinfo);
newinfo->director_name = malloc(len + 1);
memcpy (newinfo->director_name,tmpname, len + 1);
memcpy (movies[n].director->director_name,tmpname,len + 1);
// movies[n].director = newinfo;
// printf("%s",movies[n].director);
printf("Enter the year of release_date:year/month/day \n");
scanf("%d%d%d", &tmpdt.year,&tmpdt.month,&tmpdt.day);
printf("done\n");
newdate->day = tmpdt.day; /* populate date struct from tmpdt struct */
newdate->month = tmpdt.month;
newdate->year = tmpdt.year;
//len=sizeof(newdate);
// movies[n].release_date = malloc(len + 1);
movies[n].release_date = newdate;
}
我原以为使用mempcy会有一个直接分配,但当我尝试打印主函数中的条目时,我键入的所有内容都是null或0,你不是在电影中丢失了图形吗?当做
movies = (movie *) malloc(sizeof(movie));
在我看来,您正在删除您从此行作为参数传递的任何数据的本地副本这是否回答了您的问题?上面的候选重复帖子引用了这一行:
movies=(movie*)malloc(sizeof(movie))代码>。正如您所发现的,这不会改变调用方的指针值。这篇文章解释了为什么以及可以做些什么来让它工作。movies[n].id=movies[n-1].id+1;电影=(电影*)malloc(电影大小)代码>。这看起来也是错误的。malloc
将分配新内存,以前的movies
数组的内容将丢失(并发生内存泄漏)。如果要增加数组的大小,您可能需要查找realloc
。