Database in C code

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

#define NUM 100 //Take 100 usernames
#define MAXLEN 20 // Max username and password length

// Function declarations
int readDatabase(char *usrDB[], int pswrdDB[]);

char *getUsername();

char *getPassword();

int searchUsername(char *username, char *usernameDB[], int size);

int attemptLogin(int passwordDB[], int idx);

int hashPassword(char *password);

int main(int argc, char **argv) {
    char *usernameDB[NUM];        // Array of pointers to strings. Will read usernames from file into this array
    int passwordDB[NUM];        // Array of ints. Will read password hashes from file into this array.
    int numUsers;                // The number of users.
    char response[MAXLEN] = {};    // Generic array for user input.

    // Read in username and password
    // YOUR CODE GOES HERE

    // Infinite loop
    while (1) {
        int usrIdx;            // Index of target username
        int loginStatus;    // Indicates whether passwords match
        char *username;        // User specified username

        //-----------------------------------------------------------
        // YOUR CODE GOES HERE
        //-----------------------------------------------------------
        numUsers = readDatabase(usernameDB, passwordDB);

        do {
            printf("Enter username: ");
            username = getUsername();
            usrIdx = searchUsername(username, usernameDB, numUsers);
            free(username);
            if (usrIdx == -1) {
                printf("Username not found\n");
            }
        } while (usrIdx == -1);

        do {
            printf("Enter your password: ");
            // Get password, hash it and compare (inside function).
            loginStatus = attemptLogin(passwordDB, usrIdx);
            if (loginStatus == 0) {
                printf("Password does not match.\n");
            }
        } while (loginStatus == 0);
        for (int i = 0; i < numUsers; i++) {
            free(usernameDB[i]);
        }
        //
        printf("Logged in.\n");
        printf("Press enter to log out.");
        fgets(response, MAXLEN, stdin);
        printf("Logged out.\n\n");

        printf("Log in to another account? (Y/N)");
        fgets(response, MAXLEN, stdin);
        if ((response[0] == 'N') || (response[0] == 'n'))
            break;
    }

    return 0;
}

// Function definitions

int readDatabase(char *usrDB[], int pswrdDB[]) {
    int numUsers = 0, numPasswords = 0;
    char userBuffer[MAXLEN];
    // open username file
    FILE *usrFP = fopen("../usernames.txt", "rt");
    if (usrFP == NULL) {
        printf("Could not open username file.\n");
        exit(1);
    }
    // read username file
    while (fgets(userBuffer, MAXLEN, usrFP) && numUsers < NUM) {
        // Allocate memory for new username.
        usrDB[numUsers] = (char *) malloc(strlen(userBuffer));
        // Check if allocation was successful.
        if (usrDB[numUsers] == NULL) {
            printf("Error allocating memory.\n");
            exit(1);
        }
        // Removes new line character from userBuffer.
        userBuffer[strlen(userBuffer) - 1] = 0;
        // Stores buffer in user database.
        strcpy(usrDB[numUsers], userBuffer);
        numUsers++;
    }
    // close username file
    fclose(usrFP);

    // open password file
    FILE *pswrdFP = fopen("../passwords.txt", "rt");
    if (pswrdFP == NULL) {
        printf("Could not open password file.\n");
        exit(1);
    }
    // read password file
    while (!feof(pswrdFP)) {
        // Scan password and increment counter
        fscanf(pswrdFP, "%d", &pswrdDB[numPasswords++]);
    }
    // close password file
    fclose(pswrdFP);

    // check number of entries the same
    if (numUsers != numPasswords) {
        printf("Number of users and passwords do not match.\n");
    }

    // return number of entries read.
    return numUsers;
}

char *getUsername() {
    char buffer[MAXLEN];
    fgets(buffer, MAXLEN, stdin);
    char *username = malloc(strlen(buffer));
    buffer[strlen(buffer) - 1] = 0;
    strcpy(username, buffer);
    return username;
}

char *getPassword() {
    char buffer[MAXLEN];
    fgets(buffer, MAXLEN, stdin);
    char *password = malloc(strlen(buffer));
    buffer[strlen(buffer) - 1] = 0;
    strcpy(password, buffer);
    return password;
}

int searchUsername(char *username, char *usernameDB[], int size) {
    int i, idx = -1;
    for (i = 0; i < size; i++) {
        if (strcmp(username, usernameDB[i]) == 0) {
            idx = i;
            break;
        }
    }
    return idx;
}

int attemptLogin(int passwordDB[], int idx) {
    // get the password using the function get password
    char *password = getPassword();
    int n = 4891;
    int hash = 0;
    // hash the password
    for (int i = 0; i < strlen(password); i++) {
        hash += password[i];
    }
    free(password);
    hash = (hash * hash) % n;
    // check hash code and return 0 or 1 appropriately
    return hash == passwordDB[idx];
}