c-resources/CPlusPlus20ForProgrammers-m.../examples/ch14/fig14_02.cpp

69 lines
2.6 KiB
C++

// fig14_02.cpp
// Algorithms fill, fill_n, generate and generate_n.
#include <algorithm> // algorithm definitions
#include <array> // array class-template definition
#include <iostream>
#include <iterator> // ostream_iterator
// returns the next letter (starts with A)
char nextLetter() {
static char letter{'A'};
return letter++;
}
int main() {
std::array<char, 10> chars{};
std::ranges::fill(chars, '5'); // fill chars with 5s
std::cout << "chars after filling with 5s: ";
std::ostream_iterator<char> output{std::cout, " "};
std::ranges::copy(chars, output);
// fill first five elements of chars with 'A's
std::ranges::fill_n(chars.begin(), 5, 'A');
std::cout << "\nchars after filling five elements with 'A's: ";
std::ranges::copy(chars, output);
// generate values for all elements of chars with nextLetter
std::ranges::generate(chars, nextLetter);
std::cout << "\nchars after generating letters A-J: ";
std::ranges::copy(chars, output);
// generate values for first five elements of chars with nextLetter
std::ranges::generate_n(chars.begin(), 5, nextLetter);
std::cout << "\nchars after generating K-O into elements 0-4: ";
std::ranges::copy(chars, output);
// generate values for first three elements of chars with a lambda
std::ranges::generate_n(chars.begin(), 3,
[]() { // lambda that takes no arguments
static char letter{'A'};
return letter++;
}
);
std::cout << "\nchars after generating A-C into elements 0-2: ";
std::ranges::copy(chars, output);
std::cout << "\n";
}
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