使用结构，C错误

Question

i am getting the error "a3.c:221:20: error: storage size of 'gold' isn't known" for all 4 of my item structs. My code is as follows:

void parser(int argc, char **argv)
{
FILE * rooms;
char * theString;
char * theToken;
int numberElements;
int side;
int k;

int placeInt;
int posX;
int posY;
char a[ROOM_STRING_LENGTH];
numberElements = 0;
rooms = fopen(argv[1], "r");

if(rooms == NULL)
{
    printf("error opening file\n");
}
while(fgets(a, ROOM_STRING_LENGTH, rooms) != NULL)
{

    theString = malloc((sizeof(char)*(strlen(a)+1)));
    strcpy(theString, a);

    for(theToken = strtok(theString, " "); theToken; theToken = strtok(NULL, " "))
    {
        printf("the next token: %s\n", theToken);
        if(theToken[0] == '1')
        {

        }
        if(theToken[0] == 'd')
        {
            switch(theToken[1])
            {
                case 'e':
                {
                    side = 1;
                    placeInt = theToken[2] - '0';
                    printf("the side: %d, the place: %d\n", side, placeInt);
                    break;
                }
                case 'w':
                {
                    side = 2;
                    placeInt = theToken[2] - '0';
                    printf("the side: %d, the place: %d\n", side, placeInt);
                    break;
                }
                case 's':
                {
                    side = 3;
                    placeInt = theToken[2] - '0';
                    printf("the side: %d, the place: %d\n", side, placeInt);
                    break;
                }
                case 'n':
                {
                    side = 4;
                    placeInt = theToken[2] - '0';
                    printf("the side: %d, the place: %d\n", side, placeInt);
                    break;
                }
                default:
                {
                    break;
                } 
            }       
        }

        else if(theToken[0] == 'g' || theToken[0] == 'm' || theToken[0] == 'p' || theToken[0] == 'h')
        {
             k = 0;
             while(k <= (strlen(theToken)))
             {

                 switch(theToken[k])
                 {
                     case 'g':
                     posY = theToken[1] - '0';
                     posX = theToken[3] - '0';
                     struct item gold;
                     gold.Xposition = posX;
                     gold.Yposition = posY;
                     printf("the y position: %d, the x position: %d\n",  posY, posX);
                     break;

                     case 'm':
                     posY = theToken[1] - '0';
                     posX = theToken[3] - '0';
                     struct item monster;
                     monster.Xposition = posX;
                     monster.Yposition = posY;
                     printf("the y position: %d, the x position: %d\n",  posY, posX);
                     break;

                     case 'p':
                     posY = theToken[1] - '0';
                     posX = theToken[3] - '0';
                     struct item potion;
                     potion.Xposition = posX;
                     potion.Yposition = posY;
                     printf("the y position: %d, the x position: %d\n",  posY, posX);
                     break;

                     case 'h':
                     posY = theToken[1] - '0';
                     posX = theToken[3] - '0';
                     struct item hero;
                     hero.Xposition = posX;
                     hero.Yposition = posY;
                     printf("the y position: %d, the x position: %d\n", posY, posX);                         
                     break;
                 }
                 k++;
             }
        }
        else if(theToken == NULL)
        {
            printf("end of file");
        }
        numberElements++;
    }

    if(theToken == NULL)
    {
        printf("You've reached the end of the line\n");
    }
    printf("%d\n", numberElements);
}

free(theString);
fclose(rooms);
}



struct item
{
    int Xposition;
    int Yposition;
};

Also, I was wondering how i would go about accessing the information i just stored into those structs in a different function.

Answer 1

As keltar and nonsensickle already mentioned, you have to define struct item before you can use an instance of it:

struct item { int x; int y; }; // this must come first

// ...

struct item item1 {4, 2};

You could, however, use a pointer before the definition, as long as you have already declared the struct:

struct item; // declaration, no definition

// ...

struct item *pitem1;

// ...

struct item { int x; int y; }; // defined later

To use a struct 's members in another function, you could pass either a struct or a struct* to that function:

void use_struct (struct item i)
{
    int a = i.x, b = i.y;
}

void use_struct_pointer (struct item *pi)
{
    int a = pi->x, b = pi->y;
}

int main()
{
    struct item i {4, 2};
    use_struct(i);
    use_struct_pointer(&i);
    return 0;
}