147 lines
3.3 KiB
C++
147 lines
3.3 KiB
C++
#include <iostream>
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#include <vector>
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#include <list>
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#include <algorithm>
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using namespace std;
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int calculateIndex(int x, int y);
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void printArray(int numbers[]);
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void printArray(int numbers[], size_t count);
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int main()
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{
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// C arrays
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int numbers[10];
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for (size_t i = 0; i < 10; i++)
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{
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numbers[i] = 0;
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}
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numbers[0] = 10;
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cout << "numbers[5]: " << numbers[5] << endl;
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int numbers2[] = { 0, 1, 2, 3, 4 };
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int numbers3[10] = { 0, 1, 2, 3, 4 };
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// 2d array - 10 rows & 5 columns
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int grid[10 * 5];
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grid[calculateIndex(3, 7)] = 10; // 4th column, 8th row
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// size/count have to be always const
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const int count = 10;
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int numbers4[count];
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int length = sizeof(numbers) / sizeof(numbers[0]); // works locally only, arrays with const length
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for (size_t i = 0; i < size(numbers2); i++) // std::size is working with locally const length arrays only
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{
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cout << numbers2[i] << " ";
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}
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cout << endl;
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printArray(numbers4);
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printArray(numbers4, size(numbers4));
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// "dynamic" heap arrays
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int count2 = 10;
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int* pNumbers = new int[count2];
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pNumbers[0] = 10;
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int* pNumber = pNumbers; // pNumber points onto the first element
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//pNumber++; // pNumber points onto the second element
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//pNumber--;
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//pNumber += 2;
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cout << "\"dynamic\" heap arrays" << endl;
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for (size_t i = 0; i < count2; i++) // CAUTION - size is not working with heap arrays, we have to remember the size of the array
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{
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cout << pNumber << ": " << *pNumber << endl;
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pNumber++;
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}
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delete[] pNumbers; // CAUTION - heap arrays have to be deleted with delete[]
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pNumbers = pNumber = nullptr;
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// 2d arrays
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int** p2dArray = new int* [10];
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for (size_t i = 0; i < 10; i++)
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{
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p2dArray[i] = new int[10];
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}
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// for delete -> delete inner arrays first
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for (size_t i = 0; i < 10; i++)
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{
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delete[] p2dArray[i];
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p2dArray[i] = nullptr;
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}
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delete[] p2dArray; // then outer array
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p2dArray = nullptr;
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// stl collections
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vector<int> numbers5;
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vector<int> numbers6 = { 0, 1, 2, 3, 4 };
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numbers5.push_back(10); // add an item at the end
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numbers5.pop_back(); // removed an item at the end
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numbers6[2] *= 2;
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vector<int> numbers7;
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numbers7.reserve(100);
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numbers7.shrink_to_fit();
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printArray(numbers6.data(), numbers6.size());
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list<int> numbersList;
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numbersList.push_back(10);
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numbersList.push_front(0);
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//numbersList[0] = 100; // random access is not available for lists
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list<int>::iterator it = numbersList.begin();
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for (; it != numbersList.end(); it++)
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{
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cout << *it << " ";
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}
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cout << endl;
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numbersList.insert(--it, 20);
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for (it = numbersList.begin(); it != numbersList.end(); it++)
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{
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cout << *it << " ";
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}
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cout << endl;
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for (int n : numbersList)
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{ }
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// https://cppreference.com/w/cpp/algorithm.html
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for_each(numbersList.begin(), numbersList.end(), [](const int& n) {
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});
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return 0;
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}
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int calculateIndex(int x, int y)
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{
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return x + y * 5;
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}
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void printArray(int numbers[])
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{
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int length = sizeof(numbers) / sizeof(numbers[0]); // works not outside of local scope
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cout << "sizeof(numbers) (printArray): " << sizeof(numbers) << endl;
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//for (size_t i = 0; i < size(numbers); i++) // std::size is not working outside of local scope
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//{
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// cout << numbers[i] << " ";
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//}
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//cout << endl;
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}
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void printArray(int numbers[], size_t count)
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{
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for (size_t i = 0; i < count; i++)
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{
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cout << numbers[i] << " ";
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}
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cout << endl;
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}
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