How to check if the string is already in an array of structures?-CodePudding

How to check if the string is already in an array of structures? The array is inside a structure and I don't know how to compare arrays inside the structure in C.

#include <stdio.h>
#include <string.h>

struct song {
    char title[30];
    char artist[30];
    char album[30];
};

typedef struct playlist {
    char sname[30];
    char asongs[10];
    int scount;

    struct song music;
} songlist;

void addPlaylist(struct playlist *menu, int i) {
    printf("Enter playlist name: ");
    scanf("%s", menu[i].sname);

    for (int j = 0; j < i; j  ) {
        if (strcmp(menu[i].sname, menu[j].sname) == 0) {
            printf("already exists!\n");
        } else {
            printf("Successfully added playlist!\n");
        }
    }
}

int main() {
   //menu. if choice == 1, go to addPlaylist func
}

I am asking the user for the name of playlist, and when a string is entered, it should be on the array sname.

When the user wants to add another playlist and enters a playlist name that is already in the array sname, the program should print already exists!; otherwise, it should add on the array.

The array is inside a structure and I'm trying to compare the arrays to check if the user's input (which is a string) already exists inside the array. I tried using for loop but I am not sure about my conditions and the components inside the strcmp function.

EDIT For example, if the user already entered multiple names like:

favorites
vibes
mood

and then, the user decided to add more playlist names then accidentally entered the name vibes which already exists in the array.

If vibes already exists, I want the program to print already exists!

I want to know how to properly check if the entered string already exists (especially if the string is inside a structure).

EDIT

Here's the output:

As you can see there's also problem in printing the successfully... and already...

CodePudding user response：

The code which demonstrates the requested adding behavior. See in-code comments for details.

#include <stdio.h>
#include <string.h>

struct song {
    char title[30];
    char artist[30];
    char album[30];
};

typedef struct playlist {
    char sname[30];
    char asongs[10];
    int scount;

    struct song music;
} songlist;

void addPlaylist(struct playlist *menu, int i) {
    char sname[30]; // use local variable for new input
    printf("Enter playlist name: ");
    scanf("%s", sname); // read into local variable

    // go over all lists to check if it already exists
    for(int j=0; j<i; j  ) {
        if(strcmp(sname, menu[j].sname)==0) {
            printf("Playlist '%s' already exists!\n", sname);
            return;
        } 
    }

    // go over all lists to search for first empty entry
    for(int j=0; j<i; j  ) {
        if(menu[j].sname[0] == '\0') {
            strcpy(menu[j].sname, sname);
            printf("Successfully added playlist '%s'!\n", menu[j].sname);
            return;
        } 
    }

    // No empty entry found
    printf("No space for new Playlist. Please remove one!\n");
}

int main() {
    songlist playlists[10];
    for (int i=0; i<10; i  ) {
        playlists[i].sname[0] = '\0'; // use string termination char to indicate unused entry
        playlists[i].asongs[0] = '\0';
        playlists[i].scount = 0;
        playlists[i].music.title[0] = '\0';
        playlists[i].music.album[0] = '\0';
        playlists[i].music.artist[0] = '\0';
    }
    char input;
    do {
        printf("======= MENU =======\n");
        printf("[1] Add Playlist\n");
        printf("[2] Add Song to Playlist\n");
        printf("[3] Remove Song from Playlist\n");
        printf("[4] View a Playlist\n");
        printf("[5] View All Data\n");
        printf("[6] Exit\n");
        scanf(" %c", &input);

        switch (input) {
            case '1': addPlaylist(playlists, 10); break;
            case '2': break;
            case '3': break;
            case '4': break;
            case '5': break;
            case '6': break;
            default: printf("Unknown selection!\n"); break;
        }
    } while (input != '6');

   return 0;
}

$ gcc -Wall playlist.c
$ ./a.out
======= MENU =======
[1] Add Playlist
[2] Add Song to Playlist
[3] Remove Song from Playlist
[4] View a Playlist
[5] View All Data
[6] Exit
1
Enter playlist name: vibes
Successfully added playlist 'vibes'!
======= MENU =======
[1] Add Playlist
[2] Add Song to Playlist
[3] Remove Song from Playlist
[4] View a Playlist
[5] View All Data
[6] Exit
1
Enter playlist name: mood
Successfully added playlist 'mood'!
======= MENU =======
[1] Add Playlist
[2] Add Song to Playlist
[3] Remove Song from Playlist
[4] View a Playlist
[5] View All Data
[6] Exit
1
Enter playlist name: favorites
Successfully added playlist 'favorites'!
======= MENU =======
[1] Add Playlist
[2] Add Song to Playlist
[3] Remove Song from Playlist
[4] View a Playlist
[5] View All Data
[6] Exit
1
Enter playlist name: vibes
Playlist 'vibes' already exists!
======= MENU =======
[1] Add Playlist
[2] Add Song to Playlist
[3] Remove Song from Playlist
[4] View a Playlist
[5] View All Data
[6] Exit
6
$

CodePudding user response：

There is a problem in addPlaylist: you should return from the function when you find a match, returning 0 to the caller so it does not add the last entry, and you should test all entries before printing Successfully added playlist!, returning 1 to the caller.

// return 1 if the playlist was added at offset i
int addPlaylist(struct playlist *menu, int i) {
    printf("Enter playlist name: ");
    if (scanf(")s", menu[i].sname) != 1)
        return 0;

    for (int j = 0; j < i; j  ) {
        if (strcmp(menu[i].sname, menu[j].sname) == 0) {
            printf("already exists!\n");
            return 0;
        }
    }
    printf("Successfully added playlist!\n");
    return i;
}