Range-v3 Range algorithms, views, and actions for the Standard Library |

Examples

# hello ranges

#include <iostream>
#include <range/v3/all.hpp> // get everything
#include <string>
using std::cout;
int
main()
{
std::string s{"hello"};
// output: h e l l o
ranges::for_each(s, [](char c) { cout << c << ' '; });
cout << '\n';
}

# any_of, all_of, none_of

// Demonstrates any_of, all_of, none_of
// output
// vector: [6,2,3,4,5,6]
// vector any_of is_six: true
// vector all_of is_six: false
// vector none_of is_six: false
#include <range/v3/algorithm/all_of.hpp>
#include <range/v3/algorithm/any_of.hpp>
#include <range/v3/algorithm/for_each.hpp>
#include <range/v3/algorithm/none_of.hpp>
#include <range/v3/view/all.hpp>
#include <iostream>
#include <vector>
using std::cout;
auto is_six = [](int i) { return i == 6; };
int
main()
{
std::vector<int> v{6, 2, 3, 4, 5, 6};
cout << std::boolalpha;
cout << "vector: " << ranges::views::all(v) << '\n';
cout << "vector any_of is_six: " << ranges::any_of(v, is_six) << '\n';
cout << "vector all_of is_six: " << ranges::all_of(v, is_six) << '\n';
cout << "vector none_of is_six: " << ranges::none_of(v, is_six) << '\n';
}

# count

// This example demonstrates counting the number of
// elements that match a given value.
// output...
// vector: 2
// array: 2
#include <iostream>
#include <range/v3/algorithm/count.hpp> // specific includes
#include <vector>
using std::cout;
int
main()
{
std::vector<int> v{6, 2, 3, 4, 5, 6};
// note the count return is a numeric type
// like int or long -- auto below make sure
// it matches the implementation
auto c = ranges::count(v, 6);
cout << "vector: " << c << '\n';
std::array<int, 6> a{6, 2, 3, 4, 5, 6};
c = ranges::count(a, 6);
cout << "array: " << c << '\n';
}

# count_if

// This example counts element of a range that match a supplied predicate.
// output
// vector: 2
// array: 2
#include <array>
#include <iostream>
#include <range/v3/algorithm/count_if.hpp> // specific includes
#include <vector>
using std::cout;
auto is_six = [](int i) -> bool { return i == 6; };
int
main()
{
std::vector<int> v{6, 2, 3, 4, 5, 6};
auto c = ranges::count_if(v, is_six);
cout << "vector: " << c << '\n'; // 2
std::array<int, 6> a{6, 2, 3, 4, 5, 6};
c = ranges::count_if(a, is_six);
cout << "array: " << c << '\n'; // 2
}

# find, find_if, find_if_not on sequence containers

// vector: *i: 6
// didn't find 10
// *i: 6
// *i: 2
// *i after ++ (2 expected): 2
// array: *i: 6
// list: *i: 6
// fwd_list: *i: 4
// deque: *i: 6
#include <array>
#include <deque>
#include <forward_list>
#include <iostream>
#include <list>
#include <range/v3/all.hpp>
#include <vector>
using std::cout;
auto is_six = [](int i) -> bool { return i == 6; };
int
main()
{
cout << "vector: ";
std::vector<int> v{6, 2, 6, 4, 6, 1};
{
auto i = ranges::find(v, 6); // 1 2 3 4 5 6
cout << "*i: " << *i << '\n';
}
{
auto i = ranges::find(v, 10); // 1 2 3 4 5 6
if(i == ranges::end(v))
{
cout << "didn't find 10\n";
}
}
{
auto i = ranges::find_if(v, is_six);
if(i != ranges::end(v))
{
cout << "*i: " << *i << '\n';
}
}
{
auto i = ranges::find_if_not(v, is_six);
if(i != ranges::end(v))
{
cout << "*i: " << *i << '\n';
}
}
{
auto i = ranges::find(v, 6);
i++;
if(i != ranges::end(v))
{
cout << "*i after ++ (2 expected): " << *i;
}
}
cout << "\narray: ";
std::array<int, 6> a{6, 2, 3, 4, 5, 1};
{
auto i = ranges::find(a, 6);
if(i != ranges::end(a))
{
cout << "*i: " << *i;
}
}
cout << "\nlist: ";
std::list<int> li{6, 2, 3, 4, 5, 1};
{
auto i = ranges::find(li, 6);
if(i != ranges::end(li))
{
cout << "*i: " << *i;
}
}
cout << "\nfwd_list: ";
std::forward_list<int> fl{6, 2, 3, 4, 5, 1};
{
auto i = ranges::find(fl, 4);
if(i != ranges::end(fl))
{
cout << "*i: " << *i;
}
}
cout << "\ndeque: ";
std::deque<int> d{6, 2, 3, 4, 5, 1};
{
auto i = ranges::find(d, 6);
if(i != ranges::end(d))
{
cout << "*i: " << *i;
}
}
cout << '\n';
}

# for_each on sequence containers

// Use the for_each to print from various containers
// output
// vector: 1 2 3 4 5 6
// array: 1 2 3 4 5 6
// list: 1 2 3 4 5 6
// fwd_list: 1 2 3 4 5 6
// deque: 1 2 3 4 5 6
#include <array>
#include <deque>
#include <forward_list>
#include <iostream>
#include <list>
#include <queue>
#include <range/v3/algorithm/for_each.hpp> // specific includes
#include <stack>
#include <vector>
using std::cout;
auto print = [](int i) { cout << i << ' '; };
int
main()
{
cout << "vector: ";
std::vector<int> v{1, 2, 3, 4, 5, 6};
ranges::for_each(v, print); // 1 2 3 4 5 6
cout << "\narray: ";
std::array<int, 6> a{1, 2, 3, 4, 5, 6};
ranges::for_each(a, print);
cout << "\nlist: ";
std::list<int> ll{1, 2, 3, 4, 5, 6};
ranges::for_each(ll, print);
cout << "\nfwd_list: ";
std::forward_list<int> fl{1, 2, 3, 4, 5, 6};
ranges::for_each(fl, print);
cout << "\ndeque: ";
std::deque<int> d{1, 2, 3, 4, 5, 6};
ranges::for_each(d, print);
cout << '\n';
}

# for_each on associative containers

// for_each with associative containers
// output
// set: 1 2 3 4 5 6
// map: one:1 three:3 two:2
// unordered_map: three:3 one:1 two:2
// unordered_set: 6 5 4 3 2 1
#include <iostream>
#include <map>
#include <range/v3/algorithm/for_each.hpp>
#include <set>
#include <string>
#include <unordered_map>
#include <unordered_set>
using std::cout;
using std::string;
auto print = [](int i) { cout << i << ' '; };
// must take a pair for map types
auto printm = [](std::pair<string, int> p) {
cout << p.first << ":" << p.second << ' ';
};
int
main()
{
cout << "set: ";
std::set<int> si{1, 2, 3, 4, 5, 6};
ranges::for_each(si, print);
cout << "\nmap: ";
std::map<string, int> msi{{"one", 1}, {"two", 2}, {"three", 3}};
ranges::for_each(msi, printm);
cout << "\nunordered map: ";
std::unordered_map<string, int> umsi{{"one", 1}, {"two", 2}, {"three", 3}};
ranges::for_each(umsi, printm);
cout << "\nunordered set: ";
std::unordered_set<int> usi{1, 2, 3, 4, 5, 6};
ranges::for_each(usi, print);
cout << '\n';
}

# is_sorted

// Check if a container is sorted
// output
// vector: true
// array: false
#include <array>
#include <iostream>
#include <range/v3/algorithm/is_sorted.hpp> // specific includes
#include <vector>
using std::cout;
int
main()
{
cout << std::boolalpha;
std::vector<int> v{1, 2, 3, 4, 5, 6};
cout << "vector: " << ranges::is_sorted(v) << '\n';
std::array<int, 6> a{6, 2, 3, 4, 5, 6};
cout << "array: " << ranges::is_sorted(a) << '\n';
}