infinite loop while there is a cin function [closed] - c++

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so i am working on an a little project the main idea of is that there library that have library items(book,magazine) and student and the main menu of the program have adding student,library item removing student library items...etc,so when i am trying to add a book it work perfect but when i am trying to add magazine it get into a infinite loop and doesn't letting me to enter value to enter other option and its my first program i may have a-lot of error using dev c++ and it not done yet the code::
#include<iostream>
#include<string>
using namespace std;
char enter;
string none,none1,none2;
int is,iff;
int B_num=0;//books number
int M_num=0;//magazine number
int S_num=0;//student number
class Clibrary_items{//the clibrary class is a class that got the common elemt of the magazine and the book
protected:
string name,publisher;
string av="availabil";//the availability of a book or a magazine
};
class Cbook: public Clibrary_items{
private:
string author_name;
public:
virtual void set(string n,string p,string a)
{
name=n;
publisher=p;
author_name=a;
}
virtual void print()//the the printer function that print the pointed book
{
cout<<"the name is::"<<name<<endl;
cout<<"the publisher is::"<<publisher<<endl;
cout<<"the author name is::"<<author_name<<endl;
}
};
class Cmagazine: public Clibrary_items{
private:
int isbn;
public:
virtual void set(string na,string pu,int i)
{
name=na;
publisher=pu;
isbn=i;
}
virtual void print()//the the printer function that print the pointed magazine
{
cout<<"the name is::"<<name<<endl;
cout<<"the publisher is::"<<publisher<<endl;
cout<<"the issue number is::"<<isbn<<endl;
}
};
class Cstudent{
friend class Clibrary;
private:
string name="";
int ID;
public:
void set(string sn,int number)
{ID=number;
name=sn;}
void print_student()//the the printer function that print the pointed student
{ cout<<"ID:"<<ID<<" ";
cout<<"student name is::"<<name<<endl;}
};
class Clibrary//the main class
{
public:
Cbook book[100];//dynamic array for books
Cmagazine magazine[100];//dynamic array for magazine
Cstudent student[100];//dynamic array for student
void print()//the main function that print the main menu and get you to everthing
{
while(enter!='q')
{
cout << "[a] Add student" << endl;
cout << "[b] Remove student" << endl;
cout << "[c] Add Item to the Library" << endl;
cout << "[d] Remove Item from the Library" << endl;
cout << "[e] Borrow Item from the Library" << endl;
cout << "[f] Return Item to the Library" << endl;
cout << "[g] Show all Library Items" << endl;
cout << "[i] Show all reserved Library items" << endl;
cout << "[j] Show all free Library items" << endl;
cout << "[k] Show all students" << endl;
cout << "[l] Show all students who borrowed items" << endl;
cout << "[m] Find the student who borrowed a specific item" << endl;
cout << "[n] Show all Items borrowed by student" << endl;
cout << "q) Quit to Windows" << endl;
cin>>enter;
switch (enter)
{
case 'a':
cout<<"please enter the name::";
cin>>none;
student[S_num].set(none,S_num);
S_num++;
break;
case 'k':
for(int i=0;i<S_num;i++)
{
student[i].print_student();
}
break;
case 'b':
cout<<"please enter the name of the student you want to remove:";
cin>>none;
for(int i=0;i<S_num;i++)
if(none==student[i].name)
student[i].name="";
break;
case 'c':
cout<<"[1].add book"<<endl;
cout<<"[2].add magazine"<<endl;
cin>>iff;
if(iff==1)
{
cout<<"please enter the name of the book:"<<endl;
cin>>none;
cout<<"please enter the publisher:"<<endl;
cin>>none1;
cout<<"please enter the author name:"<<endl;
cin>>none2;
book[B_num].set(none,none1,none2);
}
if(iff==2)
{
cout<<"please enter the name of the magazine:"<<endl;
cin>>none;
cout<<"please enter the publisher:"<<endl;
cin>>none1;
cout<<"please enter the issue number:"<<endl;
cin>>is;
magazine[M_num].set(none,none1,is);
}
break;
}
}
}
};
main()
{
cout <<"****** ****** ****** ****** ****** ******" << endl;
cout <<"* *" << endl;
cout <<"****** Library Management System ******" << endl;
cout <<"* *" << endl;
cout <<"* BY: <M.Saed Ramadan> *" << endl;
cout <<"* *" << endl;
cout <<"****** ****** ****** ****** ****** ******" << endl;
Clibrary librarby;
librarby.print();
}

Answer 1

To make your code more manageable, I suggest you use function calls in your switch statement:
switch (selection) // "enter" is such a bad name.
{
case 'a':
Add_Student();
break;
case 'b':
Remove_Student();
//...
default:
cout << "Invalid menu selection, try again.\n";
break;
}
This simplification (for easy reading) leads to the following table driven menu system:
// Declare a function pointer syntax
typedef void (*Function_Pointer)(void);
struct Menu_Entry
{
char selection_char;
Function_Pointer menu_function;
};
// The table
const Menu_Entry First_Menu[] =
{
{'a', Add_Student}, // A selection entry
{'b', Remove_Student},
//...
};
const unsigned int Number_Of_Selections =
sizeof(First_Menu) / sizeof(First_Menu[0]);
// The lookup engine
char selection; // This you input from user.
for (unsigned int i = 0; i < Number_Of_Selections; ++i)
{
if (selection == First_Menu[i].selection_char)
{
// Execute the function associated with the selection
First_Menu[i].menu_function();
break;
}
}
An advantage to the table system is that you can easily add a menu selection item by:
Creating a function to perform the selection.
Adding a Menu_Item entry to the table.
That's it. Quite simple.
Which allows you to get the menu selection process working for one selection, then work on another; piece by piece.
By placing the functions in separate files, you only need to compile the lookup table source and the new selection source files. All the other code remains untouched. Much faster build times.