File Access Methods in C++

I have discussed the concept of "files" in my previous blog.Today I am discussing the different file access method.

File access Method

The way in which a file can be accessed is called file access method.It depends on the manner in which data is stored in the files.Different file access methods are given below:

Sequential Access Method:

                                                                   It is used to access data in the same manner in which it is stored in a file.This method reads and writes data in a sequence.In order to access the last record,it has to to read all the records before the last one.

The record is not fixed in this access method.It means that each record occupies different amount of memory.

One of its advantages is that memory is not wasted.One of its disadvantages is that it takes very long time to search a record.For example,if the user wants to search the 4th record,it has to read the first 3 records to access the 4th record.

Random Access Method:

                                          It is used to access the data directly without accessing the preceding data.This method does not read or write data in a sequence.It is faster than sequential access method.

It stores data in fixed length records.This is the main disadvantage of this access method.It wastes memory space.Suppose a record of 10 bytes is used to store a complete sentence in a file.If a sentence consists of a single letter like 'H', it will occupy 10 bytes to store this letter.

However,this method speeds up access time because the position of each record can be determined easily as each record takes fixed length.Database management systems store files in a random access format.

Concept of files in C++

Many students are confused with the concept of file handling in C++.So,today I will give you a little introduction about the concept of files in C++ which the essence of file handling.This would be a series of blogs which will help you to understand this concept easily.So,stay tuned !!1

Concept of files

As we see that a program inputs data from the user and stores it in variables.The data stored in the variables is temporary.When the program ends,all data stored in variables is also destroyed. The user has  to input data again from keyboard when the program is executed next time. the data has to be entered each time the program is executed that wastes time. The user may also type wrong data at different times.

Definition of files

A file is a collection of related records.It stores data about an entity(if you are unfamiliar with the concept of entity, remember that an entity is an object about which data is to be gathered.e.g., student is an entity). A data file can be used to provide input to a program.In can also be used to store the output of a program permanently.

Advantages of files

Now we will discuss the advantages of files in C++.

• Files can store large amount of data permanently.
• Files can be updated easily.
• One file can be used by many programs for same input.
• Files save time and effort to input data via keyboard.

Types of files

C++ provides two types of files.This categorization is based on how data is stored in files. Following are the types of files in C++.

Text files

A type of file that stores data as readable and printable characters in called text file.A source program of C++ is an example of text file.

Binary files

A type of file that stores data as non-readable binary code is called binary file.An object file of a C++ program is an example of binary file.

Reference

This reference of this article is taken from the book,Object Oriented Programming using C++(IT series).

Programmer in a trouble

Programmer in a trouble

Would you react like this crazy programmer in the following situation?

Turning programmer into a beast

As you know that the semi-colon is normally used to terminate a statement in the field of programming.A programmer tries not to miss semi-colon in his program otherwise his program would be full of errors.

 Do you want to turn a programmer into a beast?

Simply delete the semi-colon from his code and see the magic !!!!

Caution: Do not stay in his room after doing this otherwise he will kill you. :-)

Comparison between C++ and Haskell

Consider that you are a "Haskell" programmer and you have to write several lines of codes to simply print "Hello World". What would be your feelings?

So,as a  C++ programmer,you should be proud of your self as you only have to write cout<<"Hello World"; to print the same statement.

Binary search in C++

"Sequential search" and "binary search" are one of the most important concepts in C++.I have  discussed the concept of sequential search previously.So, today I am going to discuss the concept of binary search in C++.

Binary search

Binary search is a quicker method of searching for value in an array.It is very quick but remember that it can only search a sorted array.It cannot be applied on an unsorted array.

Procedure

The following steps should be followed to search a number in an array by this method.

• It locates the middle element of array and compares with the search number.
• If they are equal, search is successful and the index of middle element is returned.
• If they are not equal, it reduces the search to half of the array.
• If the search number is less than the middle element,it searches the first half of array.Otherwise it searches the second half of the array.The process continues until the required number is found or loop completes without successful search.

The following program demonstrates the concept of binary search in C++.

Source code

#include<iostream>

#include<conio.h>

using namespace std;

void main( )

{

int array[10]={10,20,30,40,50,60,70,80,90,100};

int n;

int mid;

int start=0

int end=9;

int loc=-1;

int i;

cout<<"Enter any number:";

cin>>n;

while(start<=end)

{

mid=(start+end)/2;

if(array[mid]==n)

{

loc=mid;

break;

}

else if(n<array[mid])

end=mid-1;

else

start=,id+1;

}

if(loc==-1)

cout<<"Number not found."<<endl;

else

cout<<"Number found at index:"<<loc<<endl;

getch( );

}

Output

Enter any number:40

Number found at index:3

Programmer-a brave person

A programmer is very brave.He is always ready to face new hardships and challenges.So,respect a programmer !!!!!!

Comparison between C++ and Java

Now you should be a proud C++ programmer !!!!

Resource

This pic has been taken from groupinfo4u.com .

C++ vs Python

C++ programmers !!! Accept the reality :-)

C++ manipulators

C++ manipulators

Manipulators are used to change/rotate the output in different styles.They are the mlost common way to control the format of output in C++.

Some of the most important manipulators that are used in C++ are:

• endl
• setw
• setprecision

Today,in my blog,I will discuss the manipulators mentioned above and their functionality in C++.

'endl' Manipulator:

                                      The word  'endl' stands for end of line.It is used to move the cursor to the beginning of the next line.It requires no parameter.

Example:

cout<<"codingwithcplusplus.blogspot.com"<<endl;

cout<<"Blogging my passion";

It will show the output as below:

codingwithcplusplus.blogspot.com

Blogging my passion

'setw' Manipulators:

                                                    The word 'setw' stands for set width.It is used to display the value of an expression in specified columns.The output is right justified by default.It is necessary to include header file "iomanip.h" to use this manipulator.

Example:

cout<<"Hello"<<setw(4)<<"World";

It will show the output as below:

Hello    World

I think no more explanation is required. :-)

'setprecision' Manipulator:

                                               It is used to set the number of digits to be displayed after decimal point.The value is rounded with the use of this manipulator.

Example:

Suppose the value of x=10.0

cout<<setprecision(2)<<x;

It will show the output as:

10.00

Now,consider

cout<<setprecision(5)<<x;

It will show the output as:

10.00000

Concept of enumeration in C++

You have often heard about "enumeration" in C++.Today I will explain this concept with the help of articles taken from different websites.

Definition of enumeration

Enum(enumeration) is a user-defined type consisting of a set of enumerators( enumerator --- named integer constant).

The idea behind enumerated types is to create new data types that can take on only a restricted range of values. Moreover, these values are all expressed as constants rather than magic numbers--in fact, there should be no need to know the underlying values.

Declaration of enumeration

The enum is declared as:

enum enum-type-name { enum-list } enum-variable;

In this form, enum-type-name is optional. However, if you want to use enum type in several places, it is better to use another way of enum declaration:

enum enum-type-name { enum-list };

//... (and somewhere below)

enum enum-type-name enum-variable;

Of course, in the second case enum-type-name cannon be omitted.

An example is given below which will show you how to declare enumeration in C++.
enum e_acomany
{
Audi,
BMW, 
Cadillac, 
 Ford,
 Jaguar, 
 Lexus, 
 Maybach, 
 RollsRoyce, 
 Saab
};

Below is a sample code that will help you to undersatnd this concept.

Source code

#include<iostream>

using namespace std;

enum colours{blue,red};

int main( )

{

colours c;

c=blue;

cout<<"Blue is at number:"<<c<<endl;

c=red;

cout<<"Red is at number:"<<c<<endl;

return 0;

}

Output

Blue is at number:0

Red is at number:1

Credits

For this blog,I have taken help from the following websites:

www.programiz.com

en.cppreference.com

www.anyexample.com

Funniest side of C++ functions

Do you agree?

C++ functions

Importance of pointers in C++

Today I found a very helpful article on "programmers.stackexchange.com" regarding the importance of pointers in C++.This article was written by David Thornley.So,I decided to share it with all my readers.

Importance of pointers in C++

Pointers are necessary for dynamic memory location, many data structures, and efficient handling of large amounts of data. Without pointers, you'd have to allocate all the program data globally or in functions or the equivalent, and you'd have no recourse if the amount of data grew beyond what you had originally allowed for. I hesitate to use absolutes here, but as far as I know all modern computer languages have pointers in some form or other.

In most languages that use pointers, there are certain sorts of references that are pointers, and perhaps certain sorts of references that aren't, and there is no further notational difference. A Lisp cons cell is a pair of pointers, although a fixnum is not a pointer. In Java, the variable used for the instance of a class is a pointer, but an int isn't. The language syntax doesn't reflect that.

C is unusual in that pointers are optional, explicit, and allow explicit pointer arithmetic. It is perfectly possible to write struct foo bar; struct foo * baz;, and once you've allocated memory for bazyou can use both bar and baz to represent struct foos. Since pointers are optional, it is useful to have notational differences. (It's essential in C++ for smart pointers, as given boost::shared_ptr<foo> bar;, bar.reset() has one meaning and bar->reset() is likely to have a much different one.)

(Actually, explicit pointers were often used in other languages when C was originally being developed, such as ^ in Pascal. C is an older language than most in common use today, and it shows.)

One of C's design goals was to write Unix in, and therefore it needed to handle memory locations in a detailed manner. (C is actually one of a family of system implementation languages common when it was being designed, another example being Cybol for Control Data computers. C is the one that became a big hit.) Therefore, it is possible to manipulate C pointers directly, assigning memory addresses and calculating new ones. This also led to some design decisions in C. C arrays are based heavily on pointer arithmetic, and indeed an array decays into a pointer in very many situations. Passing variables to C functions by reference is done by pointer. There was no strong need for arrays and passing variables by reference in the form that other contemporary languages had, so C didn't get those.

So, the answer is that, in most languages nowadays, you use pointers constantly without being reminded of the fact. In C, and to a lesser extent C++, you use pointers either to do low-level things, or as accomplish higher-level things that there's no special notation for.

Real programmer

Are you a real programmer????
See this image and decide !!!
(This image has been taken from www.sisodia.com)

Pointer Declaration in C++

Pointer Declaration

As I have discussed in the previous blog that a pointer is a variable whose value is the address of another variable.Remember that the declaring a pointer is same as declaring a simple variable.An asterisk "*" is used in the declaration that indicates that the variable is a pointer variable.

Syntax

The syntax of declaring a pointer is as follows:

DataType *var;

Example

int *p;

Now,I will demonstrate this concept by a simple program.

Source code

#include<iostream>

#include<conio.h>

using namespace std;

void main( )

{

int n;

int *ptr; // it indicates that "ptr" is a pointer

cout<<"Enter an integer";

cin>>n;

ptr=&n;

cout<<"The value of n:"<<n<<endl;

cout<<"The address of n:"<<ptr<<endl;

getch( );

}

Output

Evolution of C

Have a look at the evolution of C#,lol !!!!!!

Evolution of C

Example of pointers in C++

As we know that a pointer is a variable whose value is the address of another variable. To demonstrate it,consider the following example.

Source code

#include <iostream>

using namespace std;

int main ()

{

   int  var1;

   cout << "Address of var1 variable: ";

   cout << &var1 << endl;

   return 0;

}

Output

Example of pointer

Reference

To know the reference of this blog,

Click here

Happiness of compiling the code successfully

What's your reaction?

Concept of pointers in C++

Pointers are an extremely powerful programming tool. They can make some things much easier, help improve your program's efficiency, and even allow you to handle unlimited amounts of data. For example, using pointers is one way to have a function modify a variable passed to it. It is also possible to use pointers to dynamically allocate memory, which means that you can write programs that can handle nearly unlimited amounts of data on the fly--you don't need to know, when you write the program, how much memory you need.      

Concept of pointers

Pointers are aptly named: they "point" to locations in memory. Think of a row of safety deposit boxes of various sizes at a local bank. Each safety deposit box will have a number associated with it so that the teller can quickly look it up. These numbers are like the memory addresses of variables. A pointer in the world of safety deposit boxes would simply be anything that stored the number of another safety deposit box. Perhaps you have a rich uncle who stored valuables in his safety deposit box, but decided to put the real location in another, smaller, safety deposit box that only stored a card with the number of the large box with the real jewelry. The safety deposit box with the card would be storing the location of another box; it would be equivalent to a pointer. In the computer, pointers are just variables that store memory addresses, usually the addresses of other variables. 

Declaration of pointers

The general form of a pointer variable declaration is:

type *var-name;

Here, type is the pointer's base type; it must be a valid C++ type and var-name is the name of the pointer variable. The asterisk you used to declare a pointer is the same asterisk that you use for multiplication. 

Reference

The reference of this blog is taken from

http://www.cprogramming.com/tutorial/lesson6.html

http://www.tutorialspoint.com/cplusplus/cpp_pointers.htmqq

       

Software engineer's life

And that is how the life of a software engineer goes on !!!