c++ read from file code example

Example 1: read a file c++

// reading a text file
#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main () {
  string line;
  ifstream myfile ("example.txt");
  if (myfile.is_open())
  {
    while ( getline (myfile,line) )
    {
      //use line here
    }
    myfile.close();
  }

  else cout << "Unable to open file"; 

  return 0;
}

Example 2: c++ files

// basic file operations
#include <iostream>
#include <fstream>
using namespace std;

int main () {
  ofstream myfile;
  myfile.open ("example.txt");
  myfile << "Writing this to a file.\n";
  myfile.close();
  return 0;
}

Example 3: How to read a file in in C++

// io/read-file-sum.cpp - Read integers from file and print sum.
// Fred Swartz 2003-08-20

#include <iostream>
#include <iomanip>
#include <fstream>
using namespace std;

int main() {
    int sum = 0;
    int x;
    ifstream inFile;
    
    inFile.open("test.txt");
    if (!inFile) {
        cout << "Unable to open file";
        exit(1); // terminate with error
    }
    
    while (inFile >> x) {
        sum = sum + x;
    }
    
    inFile.close();
    cout << "Sum = " << sum << endl; 
    return 0;
}

Example 4: c++ read text file to string

#include <fstream>
#include <string>
using namespace std;

int main()
{
  ifstream ifs("myfile.txt");
  //Two ways:
  
  //Assign it at initialization
  string content( (istreambuf_iterator<char>(ifs) ),
                  (istreambuf_iterator<char>()    ) );
  
  //Assign it after initialization
  content.assign( (istreambuf_iterator<char>(ifs) ),
                  (istreambuf_iterator<char>()    ) );
  return 0;
}

Example 5: read text from file c++

#include<iostream>
#include<fstream>

using namespace std;

int main() {

 ifstream myReadFile;
 myReadFile.open("text.txt");
 char output[100];
 if (myReadFile.is_open()) {
 while (!myReadFile.eof()) {


    myReadFile >> output;
    cout<<output;


 }
}
myReadFile.close();
return 0;
}

Example 6: file reading c++

int a, b;
    
ifstream bd; 
myfile.open("file.txt");

if (myfile.is_open())
	while (bd >> a >> b)
    	cout << a << b << endl;

else cout << "ERROR";