In C++ development, the iostream standard library is utilized, offering the cin and cout functions for input and output operations correspondingly.
To perform reading and writing operations on files, we utilize the fstream library provided by C++. Now, let's explore the data types defined within the fstream library:
| Data Type | Description |
|---|---|
| fstream | It is used to create files, write information to files, and read information from files. |
| ifstream | It is used to read information from files. |
| ofstream | It is used to create files and write information to the files. |
C++ FileStream example: writing to a file
Let's explore a basic illustration of how to write to a text file named testout.txt using C++ FileStream programming.
Example
Example
#include <iostream>
#include <fstream>
using namespace std;
int main () {
ofstream filestream("testout.txt");
if (filestream.is_open())
{
filestream << "Welcome to javaCppTutorial.\n";
filestream << "C++ Tutorial.\n";
filestream.close();
}
else cout <<"File opening is fail.";
return 0;
}
Output:
Output
The content of a text filetestout.txtis set with the data:
Welcome to javaCppTutorial.
C++ Tutorial.
C++ FileStream example: reading from a file
Let's explore a basic illustration of how to read from a text file named testout.txt using C++ FileStream programming.
Example
Example
#include <iostream>
#include <fstream>
using namespace std;
int main () {
string srg;
ifstream filestream("testout.txt");
if (filestream.is_open())
{
while ( getline (filestream,srg) )
{
cout << srg <<endl;
}
filestream.close();
}
else {
cout << "File opening is fail."<<endl;
}
return 0;
}
Note: Before running the code a text file named as "testout.txt" is need to be created and the content of a text file is given below: Welcome to javaCppTutorial. C++ Tutorial.
Output:
Output
Welcome to javaCppTutorial.
C++ Tutorial.
C++ Read and Write Example
Let's explore a basic illustration of writing information to a text file named testout.txt and subsequently retrieving the data from the file utilizing C++ FileStream coding.
Example
Example
#include <fstream>
#include <iostream>
using namespace std;
int main () {
char input[75];
ofstream os;
os.open("testout.txt");
cout <<"Writing to a text file:" << endl;
cout << "Please Enter your name: ";
cin.getline(input, 100);
os << input << endl;
cout << "Please Enter your age: ";
cin >> input;
cin.ignore();
os << input << endl;
os.close();
ifstream is;
string line;
is.open("testout.txt");
cout << "Reading from a text file:" << endl;
while (getline (is,line))
{
cout << line << endl;
}
is.close();
return 0;
}
Output:
Output
Writing to a text file:
Please Enter your name: Nakul Jain
Please Enter your age: 22
Reading from a text file: Nakul Jain
22
