C++怎么进行数据验证 C++数据验证的常用方法与示例

#include <iostream>
#include <string>
#include <sstream>

bool isInteger(const std::string& str) {
  std::istringstream iss(str);
  int num;
  iss >> num;
  return iss.eof() && !iss.fail();
}

int main() {
  std::string input;
  std::cout << "请输入一个整数：";
  std::cin >> input;

  if (isInteger(input)) {
    std::cout << "输入的是一个整数。" << std::endl;
  } else {
    std::cout << "输入的不是一个整数。" << std::endl;
  }

  return 0;
}

#include <iostream>

int main() {
  int age;
  std::cout << "请输入您的年龄：";
  std::cin >> age;

  if (age >= 0 && age <= 150) {
    std::cout << "年龄有效。" << std::endl;
  } else {
    std::cout << "年龄无效。" << std::endl;
  }

  return 0;
}

#include <iostream>
#include <string>
#include <regex>

bool isValidEmail(const std::string& email) {
  const std::regex pattern(
      "(\w+)(\.|_)?(\w*)@(\w+)(\.(\w+))+");
  return std::regex_match(email, pattern);
}

int main() {
  std::string email;
  std::cout << "请输入您的电子邮件地址：";
  std::cin >> email;

  if (isValidEmail(email)) {
    std::cout << "电子邮件地址有效。" << std::endl;
  } else {
    std::cout << "电子邮件地址无效。" << std::endl;
  }

  return 0;
}

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

bool isUsernameAvailable(const std::string& username, const std::vector<std::string>& existingUsernames) {
  for (const auto& existingUsername : existingUsernames) {
    if (username == existingUsername) {
      return false; // Username already exists
    }
  }
  return true; // Username is available
}

int main() {
  std::string newUsername;
  std::vector<std::string> existingUsernames = {"user1", "user2", "user3"};

  std::cout << "请输入您想要注册的用户名：";
  std::cin >> newUsername;

  if (isUsernameAvailable(newUsername, existingUsernames)) {
    std::cout << "用户名可用。" << std::endl;
  } else {
    std::cout << "用户名已被占用。" << std::endl;
  }

  return 0;
}

#include <iostream>
#include <string>

// 验证器接口
class Validator {
public:
  virtual bool isValid(const std::string& value) = 0;
  virtual ~Validator() {}
};

// 整数验证器
class IntegerValidator : public Validator {
public:
  bool isValid(const std::string& value) override {
    try {
      std::stoi(value);
      return true;
    } catch (const std::exception& e) {
      return false;
    }
  }
};

// 范围验证器
class RangeValidator : public Validator {
public:
  RangeValidator(int min, int max) : min_(min), max_(max) {}
  bool isValid(const std::string& value) override {
    try {
      int num = std::stoi(value);
      return num >= min_ && num <= max_;
    } catch (const std::exception& e) {
      return false;
    }
  }
private:
  int min_;
  int max_;
};

int main() {
  IntegerValidator integerValidator;
  RangeValidator rangeValidator(10, 20);

  std::string input = "15";

  if (integerValidator.isValid(input) && rangeValidator.isValid(input)) {
    std::cout << "Valid input." << std::endl;
  } else {
    std::cout << "Invalid input." << std::endl;
  }

  return 0;
}