Printing a Variable

In Java We Can Print The Value Of Variable by using a '+' symbol like as shown in following program 

Program :

public class JavaApplication1 {

    public static void main(String[] args) {

        int a=15;

        System.out.println("Value Is :"+a);

    }

}

Output:

Printing sum of two variables :

public class JavaApplication1 {

    public static void main(String[] args) {
        int a=15,b=10;
        System.out.println("Sum Is :"+(a+b));
    }
}

Output:

JAVA BASICS Hello World

Java is a high-level programming language originally developed by Sun Microsystems
which was initiated by James Gosling  and released in 1995.

Java Basic Program Hello World :

public class JavaApplication1

 {

    public static void main(String[] args)   //main function

    {

        System.out.println("Hello World");  //for output

    }

    

 }

Output:

Points To Remember:
1. Java is case sensitive so be careful about upper case and lower case alphabets.
2. While using Netbeans the name of class must be same as project name and using Notepad the name of file must be same as the class name with .java extension.
3.Rules for identifiers must be followed.

Project: Banking System

Description: The C++ programs on BANKING SYSTEM has account class with data members like account number, name, deposit, withdraw amount and type of account. Customer data is stored in a binary file. A customer can deposit and withdraw amount in his account. User can create, modify and delete account.

Code:

#include<iostream>
#include<fstream>
#include<stdlib.h>
using namespace std;
class Account
{
char name[30];
int deposit;
char type[10];
public:
long long account_no;
void getdata()
{
cout<<"Enter Name =";
cin.ignore();
cin.getline(name,30);
cout<<"Enter Type of Account =";
cin>>type;
cout<<"Enter Initial Deposit =";
cin>>deposit;
cout<<"Enter Account Number =";
cin>>account_no;
}
void putdata()
{   cout<<"\n*********************";
cout<<"\nName="<<name;
cout<<"\nAccount Number="<<account_no;
cout<<"\nBalance= "<<deposit;
cout<<"\nType= "<<type<<"\n";
}
void depposit()
{
int x;
cout<<"Enter Amount To Deposit =";
cin>>x;
deposit=deposit+x;
cout<<"\nAmount Deposited\nNew Balance is "<<deposit;
}
void withdraw()
{
int x;
cout<<"Enter Amount To Withdraw ";
cin>>x;
if(x<deposit)
{
deposit=deposit-x;
cout<<"\nNew Balance "<<deposit;
   }
   else
   {
    cout<<"\nNot Enough Balance";
}
   }
void modify()
{
cout<<"\nEnter Name =";
cin.ignore();
cin.getline(name,30);
cout<<"Enter Type of Account=";
cin>>type;
}
};
main()
{
    Account a;
    int password;
cout<<"\n****Welcome To Abc Bank****\n";
int x;
cout<<"\nEnter Password: ";
cin>>password;
if(password==1507623)
{   system("cls");
cout<<"\nChoose From Menu Below\n";
while(1)
{
cout<<"\n\nPress\n1. To Create An Account\n2. To Modify An Account\n3. To Display An Account\n4. To Delete An Account\n5. To Display All Accounts\n6. To Deposit Amount\n7. To Withdraw Amount\n8. To Exit\n";
cin>>x;
system("cls");
switch(x)
{
case 1:
{
ofstream fout("Banking.bin",ios::app | ios::binary);
cout<<"Enter Details\n";
a.getdata();
fout.write((char *)&a,sizeof(a));
fout.close();
break;
}
case 2:
   {
cout<<"Enter Account Number ";
   long long y;char ch;
   int flag=0;
   cin>>y;
   fstream file("Banking.bin",ios::in | ios::binary | ios::out);
while(file&&flag==0)
{  
file.read((char *)&a,sizeof(Account));
if(a.account_no==y)
{
cout<<"Enter New Details\n";
a.modify();
                     file.seekp(-(sizeof(Account)), ios::cur);
file.write((char *) &a,sizeof(Account));
flag=1;
}
}
if(flag==0)
{
cout<<"Invalid Account Number";
}
file.close();
   break;
}
                    case 3:

{
cout<<"\nEnter Account Nunber ";
long long y;
cin>>y;
ifstream fin("Banking.bin",ios::binary);
int flag=0;

while(fin&&flag==0)
{   fin.read((char *)&a,sizeof(Account));
if(a.account_no==y)
{
cout<<"\nDetails Are\n";
a.putdata();
flag=1;
}
}
if(flag==0)
{
cout<<"Invalid Account Number";
}
fin.close();
break;
}
   case 4:
               {
            cout<<"\nEnter Account Nunber ";
long long y;
cin>>y;
fstream fin("Banking.bin",ios::binary |ios::in);
fstream file("Bank2.bin",ios::binary | ios::out);
fin.seekg(0,ios::beg);
while(fin.read((char *)&a,sizeof(Account)))
{
if(a.account_no!=y)
{ file.write((char *)&a,sizeof(Account));}
}
fin.close();
file.close();
remove("Banking.bin");
rename("Bank2.bin","Banking.bin");
cout<<"\nRecord Deleted\n";
break;
               }

case 5:
{
ifstream fin("Banking.bin",ios::binary);
while(fin.read((char *)&a,sizeof(Account)))
{
a.putdata();
   }
   fin.close();
     break;
   }
case 6:
{
cout<<"\nEnter Account Nunber ";
long long y;
cin>>y;
fstream fin("Banking.bin",ios::binary | ios::in | ios::out);
int flag=0;
while(fin&&flag==0)
{   fin.read((char *)&a,sizeof(Account));
if(a.account_no==y)
{
  a.depposit();
                    fin.seekp(-(sizeof(Account)),ios::cur);
fin.write((char *)&a,sizeof(Account));
  flag=1;
}
   }
if(flag==0)
{
cout<<"Invalid Account Number";
}
          fin.close();
  break;
           }
case 7:
{
cout<<"\nEnter Account Nunber ";
long long y;
cin>>y;
fstream fin("Banking.bin",ios::binary | ios::in | ios::out);
int flag=0;
while(fin&&flag==0)
{   fin.read((char *)&a,sizeof(Account));
if(a.account_no==y)
{
 a.withdraw();
    fin.seekp(-(sizeof(Account)),ios::cur);
fin.write((char *)&a,sizeof(Account));
  flag=1;
}
   }
if(flag==0)
{
cout<<"Invalid Account Number";
}
     fin.close();
 break;
           }
                case 8:
    exit(1);
   default: cout<<"\a\nInvalid Choice \t Try Again";
    }
    }
}
else
{
cout<<"\a\nInvalid Password";
}
}

Output:

Pointer Arithmetic

Pointer Arithmetic involves the following operations
1.Increment / Decrement pointer
2.Addition  / Subtraction of integer
3.Subtraction of Two Pointers

Following Program Illustrates the Concept:

#include<iostream>
using namespace std;
main()
{
int a[3]={1,2,3};
int *p,*q;
p=&a[0];
q=&a[2];
//incrementing decrementing
cout<<"Value"<<"\t"<<"Address"<<"\n";
cout<<*p<<"\t"<<p<<"\n";
p++;
cout<<*p<<"\t"<<p<<"\n";
p--;
cout<<*p<<"\t"<<p<<"\n";
// addition and subtraction of integer
p+=2;
cout<<*p<<"\t"<<p<<"\n";
p-=2;
cout<<*p<<"\t"<<p<<"\n";
//subtaction of two pointers
cout<<"q-p= ";
cout<<q-p;
}

Output:

File Opening Modes App(append) vs Ate(at the end)

Both Ate and App makes the file pointer points to the end of file,but there is a difference in these two.
That during App mode we cannot change the position of pointer using seekg i.e "No Modify"
While in Ate mode we can change the position of pointer using seekg i.e "Modify Allowed".

Following Program Illustrates the concept:

#include<iostream>
#include<fstream>
using namespace std;
main()
{ int a;
fstream file("file.txt",ios::in|ios::out|ios::app);
    fstream file2("file2.txt",ios::in|ios::out|ios::ate);
file<<1507;
file2<<1507;
file.seekg(0,ios::beg);
file2.seekg(0,ios::beg);
file<<623;
file2<<623;
file.close();
file2.close();
}

Special Thanks To Miss Naina Thaman For This Program.

File Output:
file.txt:                                                                                file2.txt:

File Copying :)

Program To Copy The Contents of One File To Another ,so that other file is Identical Except Every Consecutive blank Space is replaced by Single Space.

#include<iostream>
#include<fstream>
using namespace std;
main()
{
ifstream fin("text.txt");
ofstream fout("text2.txt");
char c=fin.get(),d;
while(fin)
{
fout.put(c);
d=fin.get();
if(c==' '&&d==' ')
{
d=fin.get();
}
c=d;
}
}

File  Output:
Text.txt

Text2.txt

File Pointers :)

Program To Illustrate the Concept of File Pointers :

#include<iostream>
#include<fstream>
using namespace std;
main()
{
char data[50];
cout<<"Enter Text ";
cin.getline(data,50);
ofstream fout("file1.txt",ios::out);
fout<<data;
fout.close();
cout<<"\nOpening The File\n";
ifstream fin("file1.txt",ios::in);
    fin.seekg(0,ios::end);
    int x=fin.tellg();
    cout<<"Total size "<<x<<" Bytes\n";
}

Output :