c-resources/CPlusPlus20ForProgrammers-m.../examples/ch13/fig13_03.cpp

66 lines
2.9 KiB
C++

// fig13_03.cpp
// Testing standard library vector class template
// element-manipulation functions.
#include <algorithm> // copy algorithm
#include <fmt/format.h> // C++20: This will be #include <format>
#include <iostream>
#include <ranges>
#include <iterator> // ostream_iterator iterator
#include <vector>
int main() {
std::vector values{1, 2, 3, 4, 5}; // class template argument deduction
std::vector<int> integers{values.cbegin(), values.cend()};
std::ostream_iterator<int> output{std::cout, " "};
std::cout << "integers contains: ";
std::copy(integers.cbegin(), integers.cend(), output);
std::cout << fmt::format("\nfront: {}\nback: {}\n\n",
integers.front(), integers.back());
integers[0] = 7; // set first element to 7
integers.at(2) = 10; // set element at position 2 to 10
// insert 22 as second element
integers.insert(integers.cbegin() + 1, 22);
std::cout << "Contents of vector integers after changes: ";
std::ranges::copy(integers, output);
integers.erase(integers.cbegin()); // erase first element
std::cout << "\n\nintegers after erasing first element: ";
std::ranges::copy(integers, output);
// erase remaining elements
integers.erase(integers.cbegin(), integers.cend());
std::cout << fmt::format("\nErased all elements: integers {} empty\n",
integers.empty() ? "is" : "is not");
// insert elements from the vector values
integers.insert(integers.cbegin(), values.cbegin(), values.cend());
std::cout << "\nContents of vector integers before clear: ";
std::ranges::copy(integers, output);
// empty integers; clear empties a collection
integers.clear();
std::cout << fmt::format("\nAfter clear, integers {} empty\n",
integers.empty() ? "is" : "is not");
}
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