C++ 함수 라이브러리에 대한 자세한 설명: 시스템 함수 확장 및 코드 최적화

#include <fstream>
#include <iostream>

int main() {
  std::ifstream inputFile("input.txt");
  if (inputFile.is_open()) {
    int number;
    inputFile >> number;
    std::cout << number << std::endl;
    inputFile.close();
  } else {
    std::cout << "Error opening file" << std::endl;
  }
  return 0;
}

#include <string>

int main() {
  std::string str = "Hello, world!";
  std::size_t found = str.find("world");
  if (found != std::string::npos) {
    std::cout << "Found \"world\" at position " << found << std::endl;
  } else {
    std::cout << "\"world\" not found" << std::endl;
  }
  return 0;
}

#include <vector>

int main() {
  std::vector<int> numbers = {1, 2, 3, 4, 5};
  for (int num : numbers) {
    std::cout << num << " ";
  }
  std::cout << std::endl;
  return 0;
}

#include <algorithm>
#include <vector>

int main() {
  std::vector<int> numbers = {1, 3, 2, 4, 5};
  std::sort(numbers.begin(), numbers.end());
  for (int num : numbers) {
    std::cout << num << " ";
  }
  std::cout << std::endl;
  return 0;
}