私はコーディングにかなり慣れていないので、リンクリストと構造を使用して難しい割り当てを与えられました。課題は、アーティストのアルバムやトラックを読み取ってノードに保存できるように、音楽データベースを作成することです。
現在、プログラムを実行すると、.txtファイルからデータを読み込んだときにノードが保存されません。最終的に、セグメンテーション違反が発生しているため、特定のポインターの使用が正しいかどうか疑問に思い始めています。私は何を間違っているのですか、そしてそれを機能させるために私が作ることができる修正はありますか？
私のコード（必要なライブラリが含まれています）：
構造とマクロの定義：
#define LINEBUFFERSIZE 256
struct song
{
char *songName_p;
int trackNumber;
struct song *nextSong_p;
};
struct disc
{
char *discName_p;
int year;
struct song *song_p;
struct disc *nextDisc_p;
};
struct artist
{
char name[20];
char *artistName_p;
struct disc *disc_p;
struct artist *nextArtist_p;
};
struct artist *end = (struct artist *) NULL; //NEW
struct artist *startPtr = (struct artist *) NULL; //NEW
struct artist *find(struct artist *, char * );//NEW
//NEW
Typedef：
typedef struct artist artist_t;
typedef struct disc disc_t;
typedef struct song song_t;
typedef struct artist *artistNodePtr;
typedef struct disc *discNodePtr;
typedef struct song *songNodePtr;
関数の定義：
void InsertArtist(struct artist *New);
artistNodePtr initializenode(char *name);
artistNodePtr findOrInsertArtist(artistNodePtr *sPtr, char *name);
discNodePtr findOrInsertDisc(discNodePtr *sPtr, char *discID, int releaseYear);
void findOrInsertSong(songNodePtr *sPtr, char *songID, int trackID);
void getNextLine(char buffer[], int bufferSize, FILE *fptr);
void printlist( struct artist *ptr );
void printnode(struct artist *ptr);
主な方法：
int main(int argc, char *argv[])
{
char name[20];
struct artist *newNodePointer;
char lineBuffer[LINEBUFFERSIZE];
artistNodePtr startPtr = NULL; /* initially the artist list is empty */
FILE *musicFile;
char *artistTemp, *discTemp, *yearTemp, *trackTemp, *songTemp;
int year, track, menu = 1;
artistNodePtr theArtist;
// discNodePtr theDisc;
if (argc==1)
{
printf(" Must supply a file name as command line argument/n");
return 0;
}
if ((musicFile = fopen(argv[1], "r")) == NULL)
{
printf ("Error opening music file. Program terminated/n");
return 0;
}
getNextLine(lineBuffer, LINEBUFFERSIZE, musicFile);
while (!feof(musicFile))
{
artistTemp = strtok(lineBuffer,";");
if (artistTemp == NULL)
{
printf("Error parsing input file; Program is terminated\n");
return 0;
}
discTemp = strtok(NULL ,";");
if (discTemp == NULL)
{
printf("Error parsing input file; Program is terminated\n");
return 0;
}
yearTemp = strtok(NULL ,";");
if (yearTemp == NULL)
{
printf("Error parsing input file; Program is terminated\n");
return 0;
}
trackTemp = strtok(NULL ,";");
if (trackTemp == NULL)
{
printf("Error parsing input file; Program is terminated\n");
return 0;
}
songTemp = strtok(NULL ,"\n");
if (songTemp == NULL)
{
printf("Error parsing input file; Program is terminated\n");
return 0;
}
year = atoi(yearTemp);
track = atoi(trackTemp);
theArtist = findOrInsertArtist(&startPtr, artistTemp);
// theDisc = findOrInsertDisc(&(theArtist->disc_p), discTemp, year);
//findOrInsertSong(&(theDisc->song_p), songTemp, track);
getNextLine(lineBuffer, LINEBUFFERSIZE, musicFile);
} /* end of while loop */
while (menu != 0)
{
printf("1 to display entire catalog \n");
printf("2 to display alls songs by a given artist\n");
printf("3 to display all songs on a given disc\n");
printf("0 to exit the library\n ");
scanf("%d", &menu);
switch (menu){
case 1: printlist(startPtr);
break;
case 2:
printf("enter an artist name");
scanf("%s", name );
newNodePointer = find(startPtr, name );
if (newNodePointer==NULL)
{
newNodePointer = initializenode(name );
InsertArtist(newNodePointer);
}
}
} /* end main */
}
関数の定義：
artistNodePtr findOrInsertArtist(artistNodePtr *sPtr, char *name )
{
sPtr = initializenode(name);
InsertArtist(sPtr);
if(!sPtr)
sPtr = find(startPtr, name);
return sPtr;
}
void printlist( struct artist *ptr ){
while(ptr!= NULL){
printnode(ptr);
ptr = ptr->nextArtist_p;
}
}
void printnode(struct artist *ptr)
{
printf("Name %s\n", ptr->name);
}
artistNodePtr initializenode(char *name)
{
struct artist *newNodePtr = (artistNodePtr)malloc(sizeof(artist_t));
if (newNodePtr != NULL)
{
newNodePtr->artistName_p = (char*)malloc((strlen(name)+1)*sizeof(char));
if (newNodePtr->artistName_p != NULL)
{
strcpy(newNodePtr->artistName_p, name);
newNodePtr->nextArtist_p = NULL;
newNodePtr->disc_p = NULL;
return newNodePtr;
}
}
}
void InsertArtist(struct artist *New)
{
//NEW
struct artist *temp, *prev;
if(startPtr == NULL)
{
startPtr = New;
end = New;
startPtr->nextArtist_p = NULL;
return;
}
temp = startPtr;
while(strcmp(temp->name, New->name) < 0)
{
temp = temp->nextArtist_p;
if(temp == NULL)
break;
}
if(temp == startPtr)
{
New->nextArtist_p = startPtr;
startPtr = New;
}
else
{
prev = startPtr;
while(prev->nextArtist_p != temp)
{
prev = prev->nextArtist_p;
}
prev->nextArtist_p = New;
New-> nextArtist_p = temp;
if(end == prev)
end = New;
}
}
struct artist *find(struct artist *newNodePointer, char *name)
{
//NEW
while (strcmp(name, newNodePointer->name )!=0)
{
newNodePointer = newNodePointer->nextArtist_p;
if (newNodePointer == NULL)
break;
}
return newNodePointer;
}
void getNextLine(char buffer[], int bufferSize, FILE *fptr)
{
char temp;
int i = 0;
buffer[0] = fgetc(fptr);
while ( (!feof(fptr)) && (buffer[i] != '\n') && i<(bufferSize-1))
{
i = i +1;
buffer[i]=fgetc(fptr);
}
if ((i == (bufferSize-1)) && (buffer[i] != '\n'))
{
temp = fgetc(fptr);
while (temp != '\n')
{
temp = fgetc(fptr);
}
}
buffer[i] = '\0';
}