learning-by-doing/c_pointers/chapter_4.c

#include <stdlib.h>
#include <stdio.h>


void displayArray(int arr[], size_t size);
void displayArrayPtr(int *arr, size_t size);


void displayArray(int arr[], size_t size) {
    for (size_t i = 0; i < size; i++) {
        // both variants are possible
        printf("%d\n", arr[i]);
        //printf("%d\n", *(arr + i));
    }
}


void displayArrayPtr(int *arr, size_t size) {
    for (size_t i = 0; i < size; i++) {
        // both variants are possible
        printf("%d\n", *(arr + i));
        //printf("%d\n", arr[i]);
    }
}


int main(void) {

    int vector[5] = {1,2,3,4,5};
    int *pv;

    pv = vector;

    printf("length of vector: %zu\n", sizeof(vector)/sizeof(int));

    int matrix[2][3] = {{1,2,3},{4,5,6}};

    for (size_t index = 0; index < 2; index++) {
        printf("&matrix[%zu]: %p  sizeof(matrix[%zu]): %zu\n",
            index, &matrix[index], index, sizeof(matrix[index]));
    }

    // pointer notation and arrays
    int value = 3;
    for (size_t index = 0; index < sizeof(vector)/sizeof(int); index++) {
        // all following operations are equivalent
        *pv++ *= value;
        //pv[index] *= value;
        //*(pv + index) *= value;
        //vector[index] *= value;
    }
    for (size_t index = 0; index < sizeof(vector)/sizeof(int); index++) {
        printf("vector[%zu]: %d\n", index, vector[index]);
    }

    // using malloc to create a one-dimensional array
    pv = (int*) malloc(5 * sizeof(int));
    for (size_t i = 0; i < 5; i++) {
        pv[i] = i + 1;
    }
    for (size_t i = 0; i < 5; ++i) {
        *(pv + i) = i + 1;
    }
    for(size_t index = 0; index < 5; index++) {
        printf("pv[%zu]: %d\n", index, pv[index]);
    }

    // passing array to function using array notation
    displayArray(vector, sizeof(vector)/sizeof(int));

    // passing array to function using pointer notation
    displayArrayPtr(vector, sizeof(vector)/sizeof(int));


    // using one-dimensional array of pointers
    {
        int *arr[5];
        for (size_t i = 0; i < 5; i++) {
            // both variants are equivalent
            arr[i] = (int*) malloc(sizeof(int));
            *arr[i] = i;
            //*(arr + i) = (int*) malloc(sizeof(int));
            //**(arr + i) = i;
        }
    }

    return 0;

}