We can combine two or more of these values by ORing them together. For example if you want to open a file in write mode and want to truncate it in case that already exists, following will be the syntax:
ofstream outfile
outfile.open("file.dat", ios::out | ios::trunc);
Similar way, you can open a file for reading and writing purpose as follows:
fstream afile;
afile.open("file.dat", ios::out | ios::in );
#include <fstream>
using namespace std;
int main() {
fstream file("abc.dat", ios::in | ios::out); // Open the file for input/output
// Perform operations on the file
// Close the file
file.close();
return 0;
}
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
ofstream outputFile("output.txt", ios::out | ios::ate); // Open the file for writing
if (outputFile.is_open())
{ // Check if the file is successfully opened
outputFile << "Hello, World!" << endl; // Write data to the file
outputFile << "This is a sample text." << endl;
outputFile.close(); // Close the file
cout << "Data written to the file." << endl;
}
else
{
cout << "Failed to open the file." << endl;
}
return 0;
}
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{
ifstream inputFile("input.txt"); // Open the file for reading
if (inputFile.is_open())
{ // Check if the file is successfully opened
string line;
while (getline(inputFile, line))
{ // Read each line from the file
cout << line << endl; // Display the line on the console
}
inputFile.close(); // Close the file
}
else
{
cout << "Failed to open the file." << endl;
}
return 0;
}
#include <fstream>
using namespace std;
int main()
{
int a, b, c;
string inputFileName = "input.txt";
string outputFileName = "output.txt";
ifstream fin;
fin.open(inputFileName);
fin >> a >> b;
c = a + b;
ofstream fout;
fout.open(outputFileName);
fout << c << endl;
fin.close();
fout.close();
return 0;
}
Make sure that you have already created a input.txt file and put any two number separated by space or newline.
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
char data[100];
ofstream outfile; // open a file in write mode
outfile.open("afile.txt");
cout << "Writing to the file " << endl;
cout << "Enter your name : ";
cin.getline(data, 100); // cin >> data;
// write inputted data into the file
outfile << data << endl;
cout << "Enter you age : ";
cin >> data;
// again write inputted data into the file
outfile << data << endl;
// close the open file
outfile.close();
// open a file in read mode
ifstream infile;
infile.open("afile.txt");
cout << "Reading from the file " << endl;
infile >> data;
// write the data at the screen
cout << data << endl;
// again read the data from the file and display it
infile >> data;
cout << data << endl;
// close the opened file
infile.close();
return 0;
}
Reference