Files in c++ - Algomentor

Files in c++ - with solved example

Hi, In this article we will talk about files in c++. and it's a related question like why we use files in c++, what its importance, and how files in c++ help us to solve some real-life problems. and we will also do some files program in c++.

files in c++

What are files in c++?

files are something that helps us to store data, information, configuration, and setting and we can access the data anytime from the files. there are many file systems we use in day to day life like .doc for a document, .txt for a text file, and .mp3 for the audio file, and .mp4 for the video file.

What is the use of files in c++?

Suppose we are making software in c++. which needs to store user data and after applying user id and password it shows the user information. in that case, we can use the file to first store user data and after user validation, we can show the data to authenticate users without using file it's very difficult to make a project.

What problem we need to phase if we don't have files in c++?

Imagine a website without database all the website that has a good name use the database because in the digital world we need to have a very strong hold on the user data. the same case goes with c++ as well so we are not able to store data in c++ without using a file system.

Learning files in c++ are easy or not?

Yes, it's very easy to learning files in c++ there is only one header file you need to include and use file function when you need to use the file in c++ we will discuss all the function of a file in detail in this article so stay with us for learning files in c++.

Types of stream in c++?
  • ofstream:- this data type is used to create a file using the c++ program and also use to write content in the file through c++ programs.
  • instream:- this data type can only be used to read the file using a c++ program.
  • fstream:- this data type has the functionality of both the data type listed above it can create a file, write a file, and also read from files in c++. we mostly use this because it can do all the functionality.

Types of mode to open a file using a c++ program?
  • app:- app stand for append means writing new content without overwriting the file and it starts writing from the end of the file. 
  • ate:- open the file and move read/write pointer at the end.
  • in:- open the file for reading.
  • out:- open a file for writing and start writing with overwriting the previous content.
  • trunc:- if the file already exists the content of the file will be truncated even before opening the file.
What is different type of file position pointer?

first, we should have a fileobject in which we apply all these files pointer.
  • fileobject.seekg(n):- it gives the nth character of the file.
  • fileobject.seekg(n,ios::cur):- it will forward the pointer n position forward.
  • fileobject.seekg(n,ios::end):- it will move pointer n position from backward.
  • fileobject.seekg(0,ios::cur):- it set the pointer position at the end of the file.

What is the header file used to implement file functions in c++?

#include<fstream> is used to implement all the files method in c++ the flow of this three-step will be as followed
  • opening the file
  • reading/writing into the file
  • close the file
How to open files in c++?

fstream fileobject;
fileobject.open("filename.txt", ios::out | ios::in);

using this method our file is now open for both reading and writing purpose

How to write in the file in c++?

fileobject << data;

using this technique we can write any data in the file where data is any string or integer.

How to read from the file in c++?

fileobject >> data;

read all the data of file and store into the data variable of the program

How to close the file in c++?

fileobject.close();

using the .close() method with a file object can help you to close the file after the program execution this id a very good practice to close the file when files are not using the program it can help you manage your file data in write way.

Now we will write a complete program of the file in which we open a file, write into the file, read from the file, and at the end, we close the file.

#include <fstream>
#include <iostream>
using namespace std;
 
int main () {
   string data;
   fstream fileobject;
   fileobject.open("file.txt", ios::in|ios::out);
   cout << "Writing to the file" << endl;
   cout << "Enter your name: "; 
   cin >> data;
   fileobject << data << endl;
   cout << "Reading from the file" << endl; 
   fileobject >> data; 
   cout <<"Name from file "<<data << endl;
   fileobject.close();
   return 0;
}

I hope you know understanding how the files in c++ are doing their work and how they can be your helping hand to remember the data and you can retrieve data anytime from the file.

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