Beispielprogramm

#include <stdio.h> //input output
#include <stdlib.h> //malloc, realloc
#include <string.h> //strcmp

//Defining Structs Album and Group
typedef struct{
    char album_name[21];
    int release_year;
    long int sales;
}Album;

typedef struct{
    int group_id;
    char group_name[21];
    int year;
    Album album[2]; //2 albums to make it easier
}Group;

//Function Declaration
Group* load_groups_from_file(Group *group, int *group_count);
void save_groups_to_file(Group *group, int group_count);
Group* add_group_to_struct(Group *group, int *group_count);
void search_group_id(Group *group,int temp, int group_count);
void search_group_name(Group *group, char buf[], int group_count);
void print_groups(Group *group, int group_count);
void find_album_after_year(Group *group, int temp, int search);
void find_best_selling_album(Group *group, int search);
Group* sort_groups(Group *group, int group_count);
int input_group_pos(Group *group, int group_count);

int main(){
    int group_count = 0;//group count
    int a;              //switch case variable
    Group *group;       //dynamic array of struct group
    char buf[50];       //for string input
    long int temp;      //for integer input
    int search;         //for searching at case 7 and 8

    while(1){   //infinite loop
        system("cls"); //clear the console
        //print menu
        printf("1. Load groups from file\n");
        printf("2. Save groups to file\n");
        printf("3. Add a group\n");
        printf("4. Search/Display a group by group id\n");
        printf("5. Search/Display a group by group name\n");
        printf("6. Display all groups\n");
        printf("7. Find the albums of a given group after a given year\n");
        printf("8. Find the best-selling album of a given group\n");
        printf("9. Sort group array by group name\n");
        printf("0. Exit\n");

        printf("Choice: ");
        scanf("%d", &a);
        switch (a){
            case 0:
                exit(0); //terminate programm
            case 1: //open file "groups.txt" and copy the groups into the array
                group = load_groups_from_file(group, &group_count); //because group_count is not a pointer we pass it's address
                break;
            case 2: //one file "groups.txt" and save the groups into the file
                save_groups_to_file(group, group_count);
                break;
            case 3: //add new group into the group array
                group = add_group_to_struct(group, &group_count);
                break;
            case 4: //search and display group with this specific id
                printf("Give a ID: ");
                scanf("%d",&temp);
                search_group_id(group, temp, group_count);  //sunarthsh poy emfanizei to sugkrothma me ID poy dinei o xrhsths
                break;
            case 5: //search and display group with specific name
                printf("Give a Groupname: ");
                scanf("%49s",buf);
                search_group_name(group, buf, group_count);
                break;
            case 6: //diplay all groups
                print_groups(group, group_count);
                break;
            case 7: //display all album of an group after a specific date
                search=input_group_pos(group, group_count);
                if(search == -1){
                    printf("No Groups Added!\n");
                    break;
                }
                printf("Give a Year: ");
                scanf("%d",&temp);
                find_album_after_year(group, temp, search);
                break;
            case 8: //display album of specific group with best sales out of the 2
                search=input_group_pos(group, group_count);
                if(search == -1){
                    printf("No Groups Added!\n");
                    break;
                }
                find_best_selling_album(group, search);
                break;
            case 9: //sort the groups alphabetically
                group = sort_groups(group, group_count);
                break;
            default:{
                printf("You must select something from above!!!\n");
                break;
            }
        }
        sleep(2); //sleep for 2 seconds
    }
}

//FUNCTIONS
Group* load_groups_from_file(Group *group, int *group_count){
    int i;
    FILE *fp; //file pointer to read from "groups.txt"
    if((fp = fopen("groups.txt", "r")) == NULL){ //checking if file exists
        perror ("groups.txt");
        return group;
    }
    fscanf(fp, "%d", group_count); //read group_count as pointer doesn't need &
    group = (Group*)malloc(*group_count * sizeof(Group)); //we need *group_count cause it's a pointer
    for(i=0; i<*group_count; i++){
        fscanf(fp, "%d %s %d", &group[i].group_id, group[i].group_name, &group[i].year);
        fscanf(fp, "%s %d %ld", group[i].album[0].album_name, &group[i].album[0].release_year, &group[i].album[0].sales);
        fscanf(fp, "%s %d %ld", group[i].album[1].album_name, &group[i].album[1].release_year, &group[i].album[1].sales);
    }
    return group;
}

void save_groups_to_file(Group *group, int group_count){
    int i;
    FILE *fp; //file pointer to write into "groups.txt"
    fp = fopen("groups.txt", "w"); //for saving you don't need to check existance cause it will create it
    fprintf(fp, "%d\n", group_count);
    for(i=0; i<group_count; i++){
        fprintf(fp, "%d %s %d\n", group[i].group_id, group[i].group_name, group[i].year);
        fprintf(fp, "%s %d %ld\n", group[i].album[0].album_name, group[i].album[0].release_year, group[i].album[0].sales);
        fprintf(fp, "%s %d %ld\n", group[i].album[1].album_name, group[i].album[1].release_year, group[i].album[1].sales);
    }
    fclose(fp);
}

Group* add_group_to_struct(Group *group, int *group_count){
    long int temp;
    char buf[50];
    if(*group_count == 0){ //if it was not created it needs malloc
        group = (Group*)malloc( (*group_count + 1) * sizeof(Group) );
    }else{
        group = (Group*)realloc(group, (*group_count + 1) * sizeof(Group));
    }
    printf("Group ID: ");
    scanf("%d",&temp);
    group[*group_count].group_id=temp;

    do {
    printf("Groupname: ");
    scanf("%49s",buf);
    } while(strlen(buf)>=20);
    strcpy(group[*group_count].group_name, buf);

    printf("Foundation Year: ");
    scanf("%d",&temp);
    group[*group_count].year=temp;

    printf("Now give 2 Albums in this Order: Name Release_Date Sale_Count\n");
    printf("Album 1: \n");
    scanf("%19s %d %ld", group[*group_count].album[0].album_name, &group[*group_count].album[0].release_year, &group[*group_count].album[0].sales);
    printf("Album 2: \n");
    scanf("%19s %d %ld", group[*group_count].album[1].album_name, &group[*group_count].album[1].release_year, &group[*group_count].album[1].sales);
    (*group_count)++; //increment group_count
    return group;
}

void search_group_id(Group *group, int temp, int group_count){
    int i;
    if(group_count == 0){ //checking emptyness
        printf("No Groups Added!\n");
        return;
    }
    for(i=0; i<group_count; i++){
        if(temp==group[i].group_id){
            printf("%d %s %d\n", group[i].group_id, group[i].group_name, group[i].year);
            printf("%s %d %ld\n", group[i].album[0].album_name, group[i].album[0].release_year, group[i].album[0].sales);
            printf("%s %d %ld\n", group[i].album[1].album_name, group[i].album[1].release_year, group[i].album[1].sales);
            printf("\n");
            break;
        }
    }
    if(i==group_count) printf("No Group has this ID!\n");
}
void search_group_name(Group *group, char buf[], int group_count){
    int i;
    if(group_count == 0){ //checking emptyness
        printf("No Groups Added!\n");
        return;
    }
    for(i=0; i<group_count; i++){
        if( strcmp(buf, group[i].group_name)==0 ){
            printf("%d %s %d\n", group[i].group_id, group[i].group_name, group[i].year);
            printf("%s %d %ld\n", group[i].album[0].album_name, group[i].album[0].release_year, group[i].album[0].sales);
            printf("%s %d %ld\n", group[i].album[1].album_name, group[i].album[1].release_year, group[i].album[1].sales);
            printf("\n");
            break;
        }
    }
    if(i==group_count) printf("No Group has this Name!\n");
}
void print_groups(Group *group, int group_count){
    int i;
    if(group_count == 0){ //checking emptyness
        printf("No Groups Added!\n");
        return;
    }
    printf("Groups: \n");
    for(i=0; i<group_count; i++){
        printf("%d %s %d\n", group[i].group_id, group[i].group_name, group[i].year);
        printf("%s %d %ld\n", group[i].album[0].album_name, group[i].album[0].release_year, group[i].album[0].sales);
        printf("%s %d %ld\n", group[i].album[1].album_name, group[i].album[1].release_year, group[i].album[1].sales);
        printf("\n");
    }
}
void find_album_after_year(Group *group, int temp, int search){
    int i;
    for(i=0; i<2; i++){
        if(group[search].year>=temp){
            printf("%s %d %ld\n", group[search].album[i].album_name, group[search].album[i].release_year, group[search].album[i].sales);
        }
    }
}
void find_best_selling_album(Group *group, int search){
    if(group[search].album[0].sales>group[search].album[1].sales){
        printf("%s %d %ld\n", group[search].album[0].album_name, group[search].album[0].release_year, group[search].album[0].sales);
    }
    else{
        printf("%s %d %ld\n", group[search].album[1].album_name, group[search].album[1].release_year, group[search].album[1].sales);
    }
}
Group* sort_groups(Group *group, int group_count){
    int i,j;
    Group swap;
    if(group_count == 0){ //checking emptyness
        printf("No Groups Added!\n");
        return group;
    }
    for(i=0; i<group_count; i++){
        for(j=0; j<group_count; j++){
            if( strcmp(group[j].group_name, group[i].group_name)>0 ){
                swap=group[i];
                group[i]=group[j];
                group[j]=swap;
            }
        }
    }
    return group;
}
int input_group_pos(Group *group, int group_count){
    int i;
    int search;
    char buf[50];
    if(group_count == 0){ //checking emptyness
        return -1;
    }
    do {
        printf("Give Groupname: ");
        scanf("%49s",buf);
        search=0;
        for(i=0; i<group_count; i++){
            if( strcmp(buf, group[i].group_name)==0 ){
                search=i;
                break;
            }
        }
        if(search==0) printf("No Group has this Name!\n");
    } while(search==0);
    return search;
}