This code implements a simple text-based database manager in C....

September 3, 2025 at 11:09 PM

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

#define DataBase "TEST/database.txt"

// Funzione per validare il input utente
int inputValido(const char *chiave) {
  regex_t regex;
  int controllo = regcomp(&regex, "^[a-zA-Z0-9]+$", REG_EXTENDED);
  if (controllo) {
    fprintf(stderr, "Errore compilazione regex\n");
    return 0;
  } else {
    controllo = regexec(&regex, chiave, 0, NULL, 0);
    regfree(&regex);

    if (!controllo) {
      return 1;
    } else {
      return 0;
    }
  }
}

//Funzione per validare se la chiave non e gia presente
int fiaPresente(const char *chiave) {

 File *file =fopen(DataBase, "r");
 
 // Controlo riga per riga se lachiave non e gia presente
 if(file) {
  char riga[512], temp[255];
  while(fgets(riga, sizeof(riga), file)) {
    sscanf(riga, "%[^:]", temp);
    if(strcmp(temp, chiave) == 0) {
      printf("Chiave gia presente.\n")
      fclose(file);
      return 1;
    }
  }
  
  fclose(file);
  return 0;
 }

}
// Funzione per aggiungere un record alla base di dati
void aggiungiRecord() {
  char chiave[255], valore[255], record[512];
  
  // Prendo in input la chaive e il valore da aggiungere alla base di dati
  printf("Inserisci chiave: ");
  fgets(chiave, sizeof(chiave), stdin);
  chiave[strcspn(chiave, "\n")] = 0;
  // Controllo se la chaive e valida e non presente gia nel file
  if(!inputValido(chiave) && !giaPresente(chiave)){
    printf("Chiave non valida.\n");
    return;
  }
  
  printf("Inserisci valore: ");
  fgets(valore, sizeof(valore), stdin);
  valore[strcspn(valore, "\n")] = 0;
  // COncateno la chiave al valore separandoli con un :
  snprintf(record, sizeof(record), "%s:%s\n", chiave, valore);
  
  // Accedo al file e concateno la nuova riga alla fine del file
  FILE *file = fopen(DataBase, "a");
  if (file) {
    fputs(record, file);
    fclose(file);
    printf("Record aggiunto.\n");
  } else {
    perror("Errore apertura database");
  }
}

// Funzione per settaciare una base di dati per dato una chiave
void cercaRecord() {
  char chiave[64], riga[512];
  // Prendo in input la chaive da cercare
  printf("Chiave da cercare: ");
  fgets(chiave, sizeof(chiave), stdin);
  chiave[strcspn(chiave, "\n")] = 0;
  
  // Accedo al file data base
  FILE *file = fopen(DataBase, "r");
  if (!file) {
    perror("Errore apertura database");
    return;
  }
  
  // Controllo riga per riga se la chiave e presente all'interno della base di dati
  int trovato = 0;
  char temp[255];
  while (fgets(riga, sizeof(riga), file)) {
    sscanf(riga, "%[^:]", temp);
    if (strcmp(riga, chiave) == 0) {
      fputs(riga, stdout);
      trovato = 1;
    }
  }
  
  if (!trovato)
    printf("Nessun record trovato.\n");

  fclose(file);
}

// Comparator per qsort
int comp(const void *a, const void *b) {
  const char *pa = *(const char **)a;
  const char *pb = *(const char **)b;
  return strcmp(pa, pb);
}

// Funzione per ordinare la base di dati
void ordinaDatabase() {
  // Accedo alla base di dati in modalita lettura
  FILE *file = fopen(DataBase, "r");
  if (!file) {
    perror("Errore apertura database");
    return;
  }

  char *righe[2048];
  int count = 0;
  char buffer[2048];
  // Salvo il contenuto del file nel buffer
  while (fgets(buffer, sizeof(buffer), file) && count < 2048) {
    // Duplico le righe salvate nel buffe in righe
    righe[count] = strdup(buffer);
    if (!righe[count]) {
      perror("malloc fallita");
      fclose(file);
      return;
    }
    count++;
  }
  fclose(file);
  
  // Funzione per il sorting delle righe
  qsort(righe, count, sizeof(char *), comp);
  
  // Apro il file in modalita scrittura
  file = fopen(DataBase, "w");
  if (!file) {
    perror("Errore scrittura database");
    for (int i = 0; i < count; i++) 
      free(righe[i]);
    return;
  }
  // Riscrivo le righe riordinate nel file
  for (int i = 0; i < count; i++) {
    fputs(righe[i], file);
    free(righe[i]);
  }
  fclose(file);

  printf("Database ordinato.\n");
}

// Funzione per la stampa della base di dati
void mostraDatabase() {
  // Accedo al file
  FILE *file = fopen(DataBase, "r");
  if (!file) {
    perror("Errore apertura database");
    return;
  }
  
  // Stampo il contenuto della base di dati riga per riga
  char riga[512];
  printf("Contenuto database:\n");
  while (fgets(riga, sizeof(riga), file)) {
    fputs(riga, stdout);
  }
  fclose(file);
}

int main() {
  int scelta;
  // In caso la base di dati non ci sia ancora lo creo
  FILE *file = fopen(DataBase, "a"); 
  if (file) 
    fclose(file);
  // Menu persistente per l'interazione utente programma
  do {
    printf("\nGestore Database di Testo\n");
    printf("1) Aggiungi Record\n");
    printf("2) Cerca Record\n");
    printf("3) Ordina Base di Dati\n");
    printf("4) Mostra Base di Dati\n");
    printf("5) Esci\n");
    printf("Scelta: ");
    if (scanf("%d", &scelta) != 1) {
      while (getchar() != '\n');
        continue;
    }
    getchar(); // consuma newline

    switch (scelta) {
      case 1: 
        aggiungiRecord(); 
        break;
      case 2: 
        cercaRecord(); 
        break;
      case 3: 
        ordinaDatabase(); 
        break;
      case 4: 
        mostraDatabase(); 
        break;
      case 5: 
        printf("Chiusura.\n"); 
        break;
      default: 
        printf("Scelta non valida.\n");
    }
  } while (scelta != 5);

  return 0;
}

This code implements a simple text-based database manager in C. It allows users to interact with a file-based database containing key-value pairs (in the format key:value). The database is stored in a text file (TEST/database.txt). Here's what the program does:

High-level Summary:

Key Features:
- Add a key:value pair to the database.
- Search for a record by key.
- Sort the database alphabetically by key.
- Display all database contents.
- Exit the program.
Menu Interaction: The program operates through a persistent menu that lets the user select the desired operation.
Database File: The database file stores each key:value pair on a new line. If the file doesn't exist, it is automatically created.

Detailed Features and Code Behavior:

1. Validation (`inputValido`):

The inputValido function uses regular expressions to check if the input key is valid:

A valid key can only contain alphanumeric characters ([a-zA-Z0-9]).
If the key doesn't match this pattern, the function returns 0.

2. Check for Duplicates (`fiaPresente`):

The fiaPresente function checks if a given key is already present in the database file:

The file is read line by line.
Each line is parsed to extract its key.
If the key matches the provided one, it indicates the key already exists.

3. Add Records (`aggiungiRecord`):

Prompts the user to input a key and value.
Validates the key using inputValido.
Checks the database using fiaPresente to ensure the key is not already in use.
If the input is valid and unique, it appends the new key:value pair to the database file.

4. Search Records (`cercaRecord`):

Prompts the user for a key and searches for it in the database file.
Reads the file line by line, extracting the key from each line.
If the specified key is found, the corresponding record is printed; otherwise, it prints "No record found."

5. Sort Database (`ordinaDatabase`):

Reads all the lines (records) from the database file into memory.
Sorts the records alphabetically by key using qsort.
Writes the sorted records back into the database file, overwriting its contents.

6. Display Database (`mostraDatabase`):

Opens the database file and displays its contents line by line.
Ensures that the entire database file is presented in the console.

7. Menu System (`main`):

Implements a persistent menu using a do-while loop.
Options:
1. Add a record.
2. Search for a record.
3. Sort the database.
4. Display the database.
5. Exit the program.
Users enter their choice (validated) and the corresponding function is invoked.

8. Error Handling:

Ensures that the database file is properly opened/closed.
Handles potential errors such as missing files or failed memory allocation during sorting.

Issues in the Code:

Missing headers: The function inputValido uses regex-related functionality, but <regex.h> is not included.
Typographical Errors:
- The function fiaPresente incorrectly declares File instead of FILE for file handling.
- Missing closing semicolons in a few places (e.g., printf("Chiave gia presente.\n") in fiaPresente).
- Function giaPresente is called in aggiungiRecord instead of the correct fiaPresente function.
Bug in Searching (cercaRecord):
- It attempts to compare the entire line (riga) with the key (chiave).
- Should extract the key portion from the file line using sscanf and compare it.
Potential Overflow:
- Fixed-size buffers may lead to overflow if inputs exceed their sizes.

Correct Usage Scenario:

The code is designed to maintain and manipulate a simple file-based key-value store. Here's an example workflow:

Run the program, initializing the file if necessary.
Use the menu to:
- Add new key:value pairs.
- Search by specifying a key.
- Sort and display records.

This provides a functional but basic interface for managing a minimalistic textual database in C.

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This code implements a simple text-based database manager in C....

High-level Summary:

Detailed Features and Code Behavior:

1. Validation (inputValido):

2. Check for Duplicates (fiaPresente):

3. Add Records (aggiungiRecord):

4. Search Records (cercaRecord):

5. Sort Database (ordinaDatabase):

6. Display Database (mostraDatabase):

7. Menu System (main):