Unexpected random characters printed by library management program

Question

I am working on a school project where I have to make a program that let the user enter information about new books, delete books or display all registered books.

The unexpected behavior is when I choose to display all books : THE SECOND BOOK'S TITLE ALWAYS print some strange random characters or about 15 empty lines while the rest remain normal.

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

typedef struct {
    int Pages,RlsYear,AtrNbr; //"Pages" stands for "the number of pages", "RlsYear" stands for "Release Year"
    char Title[128],Genre[128],Authors[256];
}book;

int main()
{
    int i,nb;
    char ch1,Tmp[128],cln; 
    book* b = malloc(1 * sizeof(book));

    nb=0;
    puts("\n Enter your choice : ");
    ch1=getch();

    while (ch1 != EOF && ch1 != 'q')
    {
        switch(ch1) {
            case 'n': // N to enter a new book
            case 'N':
            {
                printf("\n enter the book's Title : ");
                gets(b[nb].Title);
                printf(" enter the book's Genre : ");
                gets(b[nb].Genre);
                printf(" how many pages does the book have ? ");
                scanf("%d",&b[nb].Pages);
                gets(cln); //i added those "gets(cln)" to avoid problems from "scanf" so you can just ignore them
                printf(" when was the book released (year)? ");
                scanf("%d",&b[nb].RlsYear);
                gets(cln);
                printf(" how many authors does this book have ? ");
                scanf("%d",&b[nb].AtrNbr);
                gets(cln);
                strcpy(b[nb].Authors,"");

                for(i=0;i<b[nb].AtrNbr;i++)
                {
                    printf("\t\t enter the %d author : ",i+1);
                    gets(Tmp);
                    strcat(b[nb].Authors,Tmp);
                    strcat(b[nb].Authors," | ");
                }
                nb=nb+1;
                book* B = realloc(b, nb+1 * sizeof(book));
                b = B;
            }
            break;

            case 'i': // I to display registered books
            case 'I':
            {
                for(i=0;i<nb;i++)
                    printf("\n %s",b[i].Title);
            }
            break;

             default:
                 printf("unknown choice !");
                 break;
        }
        puts("\n Enter your choice : ");
        ch1=getch();
    }
    return 0;
}

Answer 1

I solved the problem when i changed the b.Title size from 128 to 60. Apparently the problem appears when the b.Title size passes 80. Can someone explain please? i'm more confused now