Counting Algorithms

Real-World Examples of Using std::ranges::none_of()

What are some real-world examples of using std::ranges::none_of() in software development?

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std::ranges::none_of() is a powerful algorithm for checking if none of the elements in a range meet a specific condition. Here are some real-world examples where this can be useful:

Example 1: Input Validation

In form validation, you might want to check that none of the input fields are empty:

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

int main() {
  std::vector<std::string> fields{
    "username", "password", "email"};

  auto isEmpty = [](const std::string& field) {
    return field.empty();  
  };

  bool allFieldsFilled = std::ranges::none_of(
    fields, isEmpty);  

  std::cout << "All fields filled: "
    << (allFieldsFilled ? "Yes" : "No");
}
All fields filled: Yes

Example 2: Security Checks

Ensure no user in a list has administrative privileges:

#include <algorithm>
#include <iostream>
#include <vector>

class User {/*...*/}; int main() { std::vector<User> users { User{"Alice", false}, User{"Bob", false}, User{"Charlie", false} }; bool noAdmins = std::ranges::none_of( users, &User::hasAdminRights); std::cout << "No admin users: " << (noAdmins ? "Yes" : "No"); }
No admin users: Yes

Example 3: Data Integrity

Check that no values in a dataset are negative:

#include <algorithm>
#include <iostream>
#include <vector>

int main() {
  std::vector<int> data {10, 20, 30, 40, 50};

  auto isNegative = [](int value) {
    return value < 0; 
  };

  bool allPositive = std::ranges::none_of(
    data, isNegative); 

  std::cout << "All values positive: "
    << (allPositive ? "Yes" : "No");
}
All values positive: Yes

Summary

  • Input Validation: Ensure all inputs are filled.
  • Security Checks: Verify no user has undesired permissions.
  • Data Integrity: Confirm all data values meet expected criteria.

Using std::ranges::none_of() helps keep your code clean, expressive, and efficient, making it easier to implement and maintain real-world software solutions.

Answers to questions are automatically generated and may not have been reviewed.

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