container examples for Operating Systems Principles

dynarray.cpp

#include <random>
#include <iostream>

#define SIZE 10

int main() {
    //a pointer to some integers - currently not allocated
    int * array = nullptr;
    //allocate space for 'size' integers
    array = new int[SIZE]; 
    int count;
    //create the random number generator
    std::mt19937 gen{};
    //fill the array
    for(count = 0; count < SIZE; ++count) {
        array[count] = gen();
    }
    //print out the array
    for(count = 0; count < SIZE; ++count) {
        std::cout << array[count] << std::endl;
    }
    //free the array - note that we must use the square bracket form of 'delete' 
    //as we used the square bracket version of new.
    delete[] array;
    return EXIT_SUCCESS;
}

stdarray.cpp

#include <random>
#include <iostream>
#include<array>

#define SIZE 10

int main() {

    //declare an array based on the std::array template: 
    std::array<int, SIZE> array;
    int count;
    //create the random number generator
    std::mt19937 gen{};
    //fill the array
    for(count = 0; count < SIZE; ++count) {
        array[count] = gen();
    }
    //print out the array
    for(count = 0; count < SIZE; ++count) {
        std::cout << array[count] << std::endl;
    }
    //no need to free the memory as that is handled at program exit - at least
    //for the array itself
    return EXIT_SUCCESS;
}

vector_pushback.cpp

#include <random>
#include <iostream>
#include <vector> // we need to include the vector library. 

#define SIZE 10

int main() {
    //We replace the pointer to the array with a vector: 
    std::vector<int> vec;
    //allocate space for 'size' integers
    int count;
    //create the random number generator
    std::mt19937 gen{};
    //we can choose to just push_back elements and the vector will automatically
    //allocate the space
    for(count = 0; count < SIZE; ++count) {
        vec.push_back(gen());
    }
    //print out the array
    for(count = 0; count < SIZE; ++count) {
        std::cout << vec[count] << std::endl;
    }
    //no need to free memory as the vector class is automatically freed. 
    return EXIT_SUCCESS;
}

vector_reserve.cpp

#include <random>
#include <iostream>
#include <vector> // we need to include the vector library. 

#define SIZE 10

int main() {
    //We replace the pointer to the array with a vector: 
    std::vector<int> vec;
    //allocate space for 'size' integers
    int count;
    //create the random number generator
    std::mt19937 gen{};
    //we reserve the space for the random numbers
    vec.reserve(SIZE);
    for(count = 0; count < SIZE; ++count) {
        vec[count] = gen();
    }
    //print out the array
    for(count = 0; count < SIZE; ++count) {
        std::cout << vec[count] << std::endl;
    }
    //no need to free memory as the vector class is automatically freed. 
    return EXIT_SUCCESS;
}