ifstream c++ 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: ifstream c++

// ifstream constructor.
#include <iostream>     // std::cout
#include <fstream>      // std::ifstream

int main () {

  std::ifstream ifs ("test.txt", std::ifstream::in);

  char c = ifs.get();

  while (ifs.good()) {
    std::cout << c;
    c = ifs.get();
  }

  ifs.close();

  return 0;
}

Example 3: c++ ifstream open

void open (const   char* filename,  ios_base::openmode mode = ios_base::in);
void open (const string& filename,  ios_base::openmode mode = ios_base::in);