Reading numbers from a file : ifstream « File Stream « C++ Tutorial






#include <fstream>
#include <iostream>
#include <iomanip>
using std::cout;
using std::endl;


int main() {
  const char* filename = "test.txt";
  std::ifstream inFile(filename);

  // Make sure the file stream is good
  if(!inFile) {
    cout << endl << "Failed to open file " << filename;
    return 1;
  }

  long n = 0;
  while(!inFile.eof()) {
    inFile >> n;
    cout << std::setw(10) << n;
  }
  cout << endl;
  return 0;
}
0         1         2         3         4         5         6         7         8         9        10        11        12        13
        14        15        16        17        18        19        20        21        22        23        24        25        26        27
        28        29        30        31        32        33        34        35        36        37        38        39        40        41
        42        43        44        45        46        47        48        49        50        51        52        53        54        55
        56        57        58        59        60        61        62        63        64        65        66        67        68        69
        70        71        72        73        74        75        76        77        78        79        80        81        82        83
        84        85        86        87        88        89        90        91        92        93        94        95        96        97
        98        99








12.9.ifstream
12.9.1.Read and display a text file line by line.
12.9.2.Display a file using ifstream.get()
12.9.3.Use ifstream.read() and ofstream.write()
12.9.4.Display a file from a given starting point
12.9.5.Reading a text file
12.9.6.Reading numbers from a file
12.9.7.Show a file from starting offset
12.9.8.Ignore up to 10 characters or until first space is found
12.9.9.ifstream: read buffer and seek file position