CPSC 120 Example of reading a file line by line, storing it in a std::vector, and then selecting random lines from the vector to print.

cpsc120_filelines_to_vector.cc

// Gist https://gist.github.com/mshafae/4d282935ea5deaf8c2e6aca83a9fcac8
// Filename cpsc120_filelines_to_vector.cc
// CompileCommand clang++ -std=c++17 cpsc120_filelines_to_vector
// Read a file line by line and place contents into a std::vector

#include <fstream>
#include <iostream>
#include <string>
#include <vector>

int main(int argc, char const *argv[]) {
  std::vector<std::string> arguments{argv, argv + argc};
  if (arguments.size() < 2) {
    std::cout << "Please provide a path to a file.\n";
    return 1;
  }
  std::string input_file_name{arguments.at(1)};
  // https://en.cppreference.com/w/cpp/io/basic_ifstream
  std::ifstream input_file_stream{input_file_name};
  if (!input_file_stream.is_open()) {
    std::cout << "Could not open the file " << input_file_name << "\n";
    return 1;
  }
  std::vector<std::string> lines;
  std::string line_buffer;
  
  while (std::getline(input_file_stream, line_buffer)) {
    lines.push_back(line_buffer);
  }

  if (input_file_stream.eof()) {
    std::cout << "End of file reached successfully!\n";
  } else if (input_file_stream.bad()) {
    std::cout << "I/O error while reading.\n";
    return 1;
  } else if (input_file_stream.fail()) {
    std::cout << "Failure: Long line.\n";
    return 1;
  }

  // When you open something, close it!
  input_file_stream.close();

  for (const std::string a_line : lines) {
    std::cout << a_line << "\n";
  }

  return 0;
}

cpsc120_random_words.cc

// Gist https://gist.github.com/mshafae/4bde90c3c116929a03730c7841fe9561
// Filename cpsc120_filelines_to_vector.cc
// Read a file line by line and place contents into a std::vector

#include <fstream>
#include <iostream>
#include <random>
#include <string>
#include <vector>

std::vector<std::string> ReadFileLinesToVector(std::string input_file_name) {
  std::ifstream input_file_stream{input_file_name};
  std::vector<std::string> lines;
  if (!input_file_stream.is_open()) {
    std::cout << "Could not open the file " << input_file_name << "\n";
    return lines;
  }
  while (input_file_stream.good()) {
    std::string line_buffer;
    std::getline(input_file_stream, line_buffer);
    lines.push_back(line_buffer);
  }
  return lines;
}

int main(int argc, char const *argv[]) {
  std::vector<std::string> arguments{argv, argv + argc};
  if (arguments.size() < 3) {
    std::cout << "Please provide a path to a file and how many random lines "
                 "you want printed.\n";
    return 1;
  }
  std::string input_file_name{arguments.at(1)};
  int n_words{stoi(arguments.at(2))};
  std::vector<std::string> lines{ReadFileLinesToVector(input_file_name)};

  std::random_device rd;
  std::default_random_engine engine(rd());
  std::uniform_int_distribution<int> uniform_distribution(0, lines.size() - 1);

  for (int count = 0; count < n_words; count++) {
    int psuedo_random_number = uniform_distribution(engine);
    std::cout << lines.at(psuedo_random_number) << "\n";
  }

  return 0;
}