Examples of
Reading Data from an Input file
//Example 1: read input from the keyboard
#include <iostream>
using namespace std;
int main()
{
int x;
cin >> x; // This will read from the keyboard
cout << x << endl; // This will write to the screen
return 0;
}
// Example 2: read input from an input file
#include <iostream>
#include <fstream>
using namespace std;
ifstream infile("in2.dat");
int main()
{
int x;
infile >> x; // This will read from the file
cout << x << endl; // This will write to the screen
infile.close();
return 0;
}
// Example 3: read input from an input file till input failure
// using a structured read loop
// also writes to an output file
#include <iostream>
#include <fstream>
using namespace std;
ifstream infile("in3.dat");
ofstream outfile("ex3.out");
int main()
{
int x;
infile >> x; // This will read from the file
while(infile) {
outfile << x << endl; // This will write to outfile
infile >> x; // This will read from the file
}
infile.close();
outfile.close();
return 0;
}