C++ LANGUAGE READ AND WRITE EXAMPLES

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C++ LANGUAGE READ AND WRITE EXAMPLES

Read & Write Example 


Following is the C++ program which opens a file in reading 
and writing mode. After writing information entered by 
the user to a file named afile.dat, the program reads 
information from the file and outputs it onto the screen: 

#include <fstream> 
#include <iostream> 
using namespace std; 
  
int main () 
{ 
     
   char data[100]; 
 
   // open a file in write mode. 
   ofstream outfile; 
   outfile.open("afile.dat"); 
 
   cout << "Writing to the file" << endl; 
   cout << "Enter your name: ";  
   cin.getline(data, 100); 
 
   // write inputted data into the file. 
   outfile << data << endl; 
 
   cout << "Enter your age: ";  
   cin >> data; 
   cin.ignore(); 
    
   // again write inputted data into the file. 
   outfile << data << endl; 
 
   // close the opened file. 
   outfile.close(); 
 
   // open a file in read mode. 
   ifstream infile;  
   infile.open("afile.dat");  
  
   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; 
} 
When the above code is compiled and executed, 
it produces the following sample input and output: 

$./a.out 

Writing to the file 

Enter your name: Zara 

Enter your age: 9 

Reading from the file 
Zara 
9 
Above examples make use of additional functions from cin 
object, like getline() function to read the line from 
outside, and ignore() function to ignore the extra 
characters left by previous read statement.