Help with library system

Hey guys and gals! I'm having a bit of problem with my C codes. I was supposed to make a program that adds, removes and views books. Yeahp, it's a Library System. Well, the problem is that when I input some text in like "Hello Hi", it would automatically jump to "Thank you for using the Library System" and would eventually exit. It happens when I input two or more words. I was able to add the books and all, and there are no errors, but when I get to that part, it does that. I can add 1-word letters like "Hello" and "Hi" and it wouldn't have any errors. Can you tell me what the problem is? :(
Here's my code!

Code:

---

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

char decide, choice;
int booknum;
struct libbooks{
char title[40];
char author[50];
} book1, book2, book3, book4, book5, bookx[99];

void viewbook();
void addbook();
void adminact();
void removebook();
void open();

main()
{ 
 int adminuser, adminpass, memberuser, memberpass, cmpadmin, cmpmember;
 char user[20], pass[20];
 
      strcpy(book1.title,"\n\t\t\t  The Legends Of Tom Sawyer    ");
      strcpy(book2.title,"\t\t\t  The Success Principles        ");
      strcpy(book3.title,"\t\t\t  The Lord Of The Rings        ");
      strcpy(book4.title,"\t\t\t  Star Wars: Clone Wars        ");
      strcpy(book5.title,"\t\t\t  Philosophy Of the Human Mind  ");
      puts("\n\n");
      puts("\t\t\t******************************");
      puts("\t\t\t*Don Bosco Technical College*");
      puts("\t\t\t******************************");
      puts("\n");
      puts("\t\t\t******************************");
      puts("\t\t\t* Welcome to Library System. *");
      puts("\t\t\t******************************");
      puts("\t\t\t\tEnter username: ");
      printf("\t\t\t\t    ");
      scanf("%s", user);
      puts("\t\t\t\tEnter password: ");
      printf("\t\t\t\t    ");
      scanf("%s", pass);
      adminuser = strcmp(user, "admin");
      adminpass = strcmp(pass, "dbtcadmin");
      memberuser = strcmp(user, "member");
      memberpass = strcmp(pass, "dbtcmember");
      if(adminuser == 0 && adminpass == 0)
      adminact();
      else if(memberuser == 0 && memberpass == 0)
      printf("Declare function");
      else printf("Cannot log in. Username and Password invalid");
      getch();
      }
void addbook()
    {
    int i;
    system("cls");
    puts("\n\n");
    puts("\t\t\t************************************\n");
    printf("\t\t    ** How many books do you want to enter? **\n");
    puts("\n\t\t\t************************************");
    printf("\n\t\t\t    You may enter up to 100 books.\n");
    puts("\n\t\t\t************************************");
    printf("\t\t\t\t\t ");
    scanf("%d", &booknum);
    printf("\t\t\t\t Enter the title(s):\n");
    printf("  \t\t\t\t");
    for (i=0;i<booknum;i++){
    printf("\n  \t\t\t\t");
    scanf("%s", bookx[i].title);
    }
    printf("\n\tBooks successfully added.\n");
    printf("\n\tDo you want to go back to the option admin system?<Y/N>");
    scanf("%c", &choice);
    choice = getch();
    switch(choice)
    {
    case 'Y': case 'y':
          return adminact();
          break;
    case 'N': case 'n':
          printf("\n\nThank you for using the Library System!");
          break;
          default: printf("\nNot one of the choices.");
          break;
          }
}

void viewbook()
{
    int x, y;
    system("cls");
    puts("\n\n");
    puts("\t\t\t********************************");
    printf("%s\n%s\n%s\n%s\n%s", book1.title, book2.title, book3.title, book4.title, book5.title);
    for(x = 0; x<booknum; x++)
    printf("\n\t\t\t  %s",bookx[x].title);
    puts("\n");
    puts("\t\t\t********************************");
    puts("\n");
    printf("\t\tDo you want to go back to the option system?<Y/N>");
    scanf("%c", &choice);
    choice = getch();
 switch(choice)
    {
    case 'Y': case 'y':
          return adminact();
          break;
    case 'N': case 'n':
          printf("\n\n\t\tThank you for using the Library System!");
          break;
          default: printf("\nNot one of the choices.");
          break;
          }
    }

void adminact()
{
    int choice;
    system("cls");
      puts("\n\n");
    puts("\t\t\t# **************************** #");
    printf("\n\t\t\t# *  What do you want to do? * #\n");
    puts("\n\t\t\t# **************************** #");
    puts("\t\t\t# **************************** #");
    puts("\n\t\t\t# * 1.    View book(s)      * #");
    puts("\t\t\t# * 2.    Add Book(s)        * #");
    puts("\t\t\t# * 3.    Remove book(s)    * #");
    puts("\t\t\t# * 4.    Return to Log-in  * #");
    puts("\n\t\t\t# **************************** #");
    printf("\t\t\t\t    ");
    scanf("%d", &choice);
    switch(choice)
    {
    case 1:
          viewbook();
          break;
    case 2:
          addbook();
          break;
    case 3:
          removebook();
          break;
    case 4:
          open();
          break;
         
    default: printf("Thank you for using the Library System!");
          }           
          }
     
void removebook(){
    int r, r1;
    int x, y;
    system("cls");
    puts("\n\n");
    puts("\t\t\t********************************");
    printf("%s\n%s\n%s\n%s\n%s", book1.title, book2.title, book3.title, book4.title, book5.title);
    for(x = 0; x<booknum; x++)
    printf("\n\t\t\t  %s",bookx[x].title);
    puts("\n");
    puts("\t\t\t********************************");
    printf("\n\t\t      Select the books you want to Remove.");
    printf("\n\n\t\t\t\t");
    r1 = getch();
    scanf("%d", &r1);
    switch(r1){
                case 1: strcpy(book1.title," ");return adminact();break;
                case 2: strcpy(book2.title," ");return adminact();break;
                case 3: strcpy(book3.title," ");return adminact();break;
                case 4: strcpy(book4.title," ");return adminact();break;
                case 5: strcpy(book5.title," ");return adminact();break;
                default: for(x = 0; x<booknum; x++)
                        strcpy(bookx[x].title," ");
                        return adminact();
               
        }
        }
void open()
{ 
 int adminuser, adminpass, memberuser, memberpass, cmpadmin, cmpmember;
 char user[20], pass[20];
 system("cls");
      puts("\n\n");
      puts("\t\t\t******************************");
      puts("\t\t\t*Don Bosco Technical College*");
      puts("\t\t\t******************************");
      puts("\n");
      puts("\t\t\t******************************");
      puts("\t\t\t* Welcome to Library System. *");
      puts("\t\t\t******************************");
      puts("\t\t\t\tEnter username: ");
      printf("\t\t\t\t    ");
      scanf("%s", user);
      puts("\t\t\t\tEnter password: ");
      printf("\t\t\t\t    ");
      scanf("%s", pass);
      adminuser = strcmp(user, "admin");
      adminpass = strcmp(pass, "dbtcadmin");
      memberuser = strcmp(user, "member");
      memberpass = strcmp(pass, "dbtcmember");
      if(adminuser == 0 && adminpass == 0)
      adminact();
      else if(memberuser == 0 && memberpass == 0)
      printf("Declare function");
      else printf("Cannot log in. Username and Password invalid");
      }

---

There, edited it. I hope it's clear enough. XD

Well you could read the "how to post code" thread, then edit your post so that your code looks like this, rather than an unindented mess.

Code:

---

int main ( ) {
    // your code should be indented to reflect the program flow
    // like this is indented away from the left hand side.
    return 0;
}

---

There. Sorry, I was in a hurry. XD

Has to do with stuff being in the input buffer. scanf will strip off the first word, but the space and following words are still there waiting.

You should use gets() instead of scanf()... There is the difference between inputing strings.....

Better use fgets() and strip newline(if you don't want) using strchr()/other methods.
http://c-faq.com/stdio/getsvsfgets.html

Use fgets(books[i],title, SIZE, stdin); for entering your books titles. Most books have multiple words, and scanf() is a poor choice overall, for user entry. (Where SIZE is a
#define SIZE 100

macro for the size of your array of structs.

The ONLY problem with fgets() is that it leaves in the newline char, in the title. Now you know how to remove it:

Code:

---

#include <string.h>  /* if you haven't done this yet */
int len;  /* a good variable name helps */

/* fgets() line of code, here, then: */
len = strlen(books[i].title);
if(books[i].title[len-1]=='\n') /* do we have a newline char in the title? */
  books[i].title[len-1]='\0'; /*overwrite the newline char, shortening the title by 1 char*/

---

I don't understand the book1, book2, book3, book4, book5 variables, at all. Why? When you need a local book struct, just create it, in the local function.

Yeah fgets().......

If you want to store newline character else just gets()....
Programmer's choice :-)

If you want to invite buffer overflow/marks deducted/ , use gets().
Otherwise use fgets() or something safer. Your choice. :D

Quote:

---

Originally Posted by Mr.777

Yeah fgets().......

If you want to store newline character else just gets()....
Programmer's choice :-)

---

In Theory, I agree with you, 777. In practice, gets() simply must be avoided for user input.

Yeah practically, we always need to put newline character for better processing.....

Well guys, thanks for the advice! I used the gets() function and it worked! Yay! But there is another downside that I discovered. Now when I use the function removebook, and I wanted to remove a book in an array, it doesn't remove anything. Any suggestions as to how it should be solved?

Here's the code again:

Code:

---


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

char decide, choice;
int booknum;
struct libbooks{
char title[40];
char author[50];
} book1, book2, book3, book4, book5, bookx[99];

void viewbook();
void addbook();
void adminact();
void removebook();
void open();
void useract();

main()
{ 
 int adminuser, adminpass, memberuser, memberpass, cmpadmin, cmpmember;
 char user[20], pass[20];
 
      strcpy(book1.title,"\n\t\t\t  The Legends Of Tom Sawyer    ");
      strcpy(book2.title,"\t\t\t  The Success Principles        ");
      strcpy(book3.title,"\t\t\t  The Lord Of The Rings        ");
      strcpy(book4.title,"\t\t\t  Star Wars: Clone Wars        ");
      strcpy(book5.title,"\t\t\t  Philosophy Of the Human Mind  ");
      puts("\n\n");
      puts("\t\t\t******************************");
      puts("\t\t\t*Don Bosco Technical College*");
      puts("\t\t\t******************************");
      puts("\n");
      puts("\t\t\t******************************");
      puts("\t\t\t* Welcome to Library System. *");
      puts("\t\t\t******************************");
      puts("\t\t\t\tEnter username: ");
      printf("\t\t\t\t    ");
      scanf("%s", user);
      puts("\t\t\t\tEnter password: ");
      printf("\t\t\t\t    ");
      scanf("%s", pass);
      adminuser = strcmp(user, "admin");
      adminpass = strcmp(pass, "dbtcadmin");
      memberuser = strcmp(user, "member");
      memberpass = strcmp(pass, "dbtcmember");
      if(adminuser == 0 && adminpass == 0)
      adminact();
      else if(memberuser == 0 && memberpass == 0)
      printf("Declare function");
      else printf("Cannot log in. Username and Password invalid");
      getch();
      }
void addbook()
    {
    int i;
    char temp;
    system("cls");
    puts("\n\n");
    puts("\t\t\t************************************\n");
    printf("\t\t    ** How many books do you want to enter? **\n");
    puts("\n\t\t\t************************************");
    printf("\n\t\t\t    You may enter up to 100 books.\n");
    puts("\n\t\t\t************************************");
    printf("\t\t\t\t\t ");
    scanf("%d%c", &booknum,&temp);
    printf("\t\t\t\t Enter the title(s):\n");
    printf("  \t\t\t\t");
    for (i=0;i<booknum;i++){
    printf("\n  \t\t\t\t");
    gets(bookx[i].title);
    }
    printf("\n\tBooks successfully added.\n");
    printf("\n\tDo you want to go back to the option admin system?<Y/N>");
    scanf("%c%c", &choice,&temp);
    //choice = getch();
    switch(choice)
    {
    case 'Y': case 'y':
          return adminact();
          break;
    case 'N': case 'n':
          printf("\n\nThank you for using the Library System!");
          break;
          default: printf("\nNot one of the choices.");
          break;
          }
}

void viewbook()
{
    int x, y;
    char temp;
    system("cls");
    puts("\n\n");
    puts("\t\t\t********************************");
    printf("%s\n%s\n%s\n%s\n%s", book1.title, book2.title, book3.title, book4.title, book5.title);
    for(x = 0; x<booknum; x++)
    printf("\n\t\t\t  %s",bookx[x].title);
    puts("\n");
    puts("\t\t\t********************************");
    puts("\n");
    printf("\t\tDo you want to go back to the option system?<Y/N>");
    scanf("%c%c", &choice,&temp);
    //choice = getch();
 switch(choice)
    {
    case 'Y': case 'y':
          return adminact();
          break;
    case 'N': case 'n':
          printf("\n\n\t\tThank you for using the Library System!");
          break;
          default: printf("\nNot one of the choices.");
          break;
          }
    }

void adminact()
{
    int choice;
    char temp;
    system("cls");
      puts("\n\n");
    puts("\t\t\t# **************************** #");
    do{ printf("\n\t\t\t# *  What do you want to do? * #\n");
    puts("\n\t\t\t# **************************** #");
    puts("\t\t\t# **************************** #");
    puts("\n\t\t\t# * 1.    View book(s)      * #");
    puts("\t\t\t# * 2.    Add Book(s)        * #");
    puts("\t\t\t# * 3.    Remove book(s)    * #");
    puts("\t\t\t# * 4.    Return to Log-in  * #");
    puts("\n\t\t\t# **************************** #");
    printf("\t\t\t\t    ");
    scanf("%d%c", &choice,&temp);
    switch(choice)
    {
    case 1:
          viewbook();
          break;
    case 2:
          addbook();
          break;
    case 3:
          removebook();
         
          break;
    case 4:
          open();
          break;
         
    default: printf("Thank you for using the Library System!");
          } 
          }while(choice != 1 &&choice != 2&&choice != 3&&choice != 4 );         
          }
     
void removebook(){
    int r, r1;
    int x, y=2;
    char temp;
    system("cls");
    puts("\n\n");
    puts("\t\t\t********************************");
    printf("%s\n%s\n%s\n%s\n%s", book1.title, book2.title, book3.title, book4.title, book5.title);
    for(x = 0; x<booknum; x++)
    printf("\n\t\t\t  %s",bookx[x].title);
    puts("\n");
    puts("\t\t\t********************************");
    printf("\n\t\t      Select the books you want to Remove.");
    printf("\n\n\t\t\t\t");
    // r1 = getch();
    scanf("%d%c", &r1,&temp);
   
    switch(r1){
                case 1: strcpy(book1.title," ");return adminact();break;
                case 2: strcpy(book2.title," ");return adminact();break;
                case 3: strcpy(book3.title," ");return adminact();break;
                case 4: strcpy(book4.title," ");return adminact();break;
                case 5: strcpy(book5.title," ");return adminact();break;
                default: for(r=1;r<booknum-y;r++)
                {
                       
                    strcpy(bookx[r].title," ");
                        y--;
                        }
                          return adminact();
                     
               
        }
        }
void open()
{ 
 int adminuser, adminpass, memberuser, memberpass, cmpadmin, cmpmember;
 char user[20], pass[20];
 system("cls");
      puts("\n\n");
      puts("\t\t\t******************************");
      puts("\t\t\t*Don Bosco Technical College*");
      puts("\t\t\t******************************");
      puts("\n");
      puts("\t\t\t******************************");
      puts("\t\t\t* Welcome to Library System. *");
      puts("\t\t\t******************************");
      puts("\t\t\t\tEnter username: ");
      printf("\t\t\t\t    ");
      scanf("%s", user);
      puts("\t\t\t\tEnter password: ");
      printf("\t\t\t\t    ");
      scanf("%s", pass);
      adminuser = strcmp(user, "admin");
      adminpass = strcmp(pass, "dbtcadmin");
      memberuser = strcmp(user, "member");
      memberpass = strcmp(pass, "dbtcmember");
      if(adminuser == 0 && adminpass == 0)
      adminact();
      else if(memberuser == 0 && memberpass == 0)
      printf("Declare function");
      else printf("Cannot log in. Username and Password invalid");
      }

---

Practically, you can't remove from the static arrays, and also you are assigning the title as " ".
So, in viewbook function, don't show the books which have title as " ".
Simple :-)

Well apart from the train wreck of using gets(), the next problem I see is your recursive calls to adminact(); every time you finish something.

viewbook() for example should just return; and it is right back in the middle of adminact() where it was called from.

If you want a normal user to call viewbook(), you would want to return to the normal user function as well.

Quote:

---

Originally Posted by Mr.777

If you want to store newline character else just gets()....
Programmer's choice :-)

---

It's good to know I can just never bother reading anything you post again.


Quzah.

Quote:

---

Originally Posted by Salem

Well apart from the train wreck of using gets(), the next problem I see is your recursive calls to adminact(); every time you finish something.

viewbook() for example should just return; and it is right back in the middle of adminact() where it was called from.

If you want a normal user to call viewbook(), you would want to return to the normal user function as well.

---

If I won't use adminact() to go back, what can I use?

Quote:

---

Originally Posted by Mr.777

Practically, you can't remove from the static arrays, and also you are assigning the title as " ".
So, in viewbook function, don't show the books which have title as " ".
Simple :-)

---

I didn't quite understand what you were pointing out. XD

OK, let's say we have a menu() function, that shows the options we can choose. We choose addBook(), and add a book. Now, how do we get back to the menu again?

We simply do nothing! :D
Sample menu code:

Code:

---

void menu() {
  int choice = 9;
  while(choice != '0') {
    printf("\n\n\n Welcome to the Library Menu\n\n");
    printf("
    1. Add a Book\n\
    2. Delete a Book\n\
    3. Edit a Book Record\n\
    4. Search for a Book\n\
    5. View all Books\n\n");

    printf("Your Choice (0 to Quit) >> ");
    scanf("%c", &choice);
    (void) getchar();
    choice = tolower(choice); //include ctype.h for tolower()

    switch(choice) {
      case 1: addBook(); break;
      case 2: etc.
      //etc.
    } //end of switch
  } //end of while
} //end of menu()

---

Without doing anything, after we call "addBook()", the program will return and execute the next code, which is "break". Then the menu will be printed up again.

No recalling the menu() function is necessary. (And if you do it, it will break your program before long).

Now say we had a main menu() and an adminMenu(), and we're at the main menu(). So we choose adminMenu() to do some admin work, then we would loop back (first), to the adminMenu() function, just by returning. If we return again, we're now back at the main menu() function.

That's how the call stack works - like a plate stack in your kitchen. You put plates on the stack, and then remove them, always by taking off the top plate, not just ANY plate. Every time you add a plate to the stack of plates, it's a PUSH, and every time you remove a plate, it's a POP. Every time you call a function, it's a PUSH of the return address, onto the stack. Every time you return from a function, it's a POP off of the stack.

And now it's time to have some lunch! :D

Quote:

---

Originally Posted by Adak

choice = tolower(choice)
[/code]

---

What does the tolower() function do? :)

Quote:

---

Originally Posted by hexarthrius

What does the tolower() function do? :)

---

Seriously? Learn to internets.


Quzah.

Quote:

---

Originally Posted by hexarthrius

What does the tolower() function do? :)

---

Look it up in your library documentation...

Ahh... Right. XD