Lernen Pointers and Arrays | Pointers in Arrays and Functions

When you declare an array in C, such as int numbers[5];, the array name (numbers) represents the address of its first element. This means that numbers can be used like a pointer of type int *. You can assign the address of numbers to a pointer variable, and then use that pointer to access or modify the elements of the array.

main.c


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#include <stdio.h>

int main() {
    int numbers[5] = {10, 20, 30, 40, 50};
    int *ptr = numbers; // Array name acts as a pointer to the first element

    printf("Accessing array using array indexing:\n");
    for (int i = 0; i < 5; i++) {
        printf("numbers[%d] = %d\n", i, numbers[i]);
    }

    printf("\nAccessing array using pointer arithmetic:\n");
    for (int i = 0; i < 5; i++) {
        printf("*(ptr + %d) = %d\n", i, *(ptr + i));
    }

    printf("\nModifying array elements using pointers:\n");
    for (int i = 0; i < 5; i++) {
        *(ptr + i) = *(ptr + i) + 1; // Increment each element by 1
        printf("numbers[%d] after increment = %d\n", i, numbers[i]);
    }

    return 0;
}

Array indexing and pointer arithmetic are closely related. Accessing numbers[i] is equivalent to using pointer arithmetic as *(numbers + i). Both expressions retrieve the value at the ith position of the array. Pointer arithmetic adds the offset (in elements, not bytes) to the base address of the array, which makes *(numbers + i) point to the correct element.

Using array indexing is typically clearer and more readable for most array operations, especially when you want to emphasize working with arrays. However, pointer arithmetic can be useful in situations where you need to traverse arrays efficiently, such as in performance-critical code or when writing functions that operate on arrays via pointers. Both techniques are interchangeable when accessing or modifying elements, but readability and code clarity should guide your choice in most programs.

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main.c


              123456789101112131415161718192021222324
            
#include <stdio.h>

int main() {
    int numbers[5] = {10, 20, 30, 40, 50};
    int *ptr = numbers; // Array name acts as a pointer to the first element

    printf("Accessing array using array indexing:\n");
    for (int i = 0; i < 5; i++) {
        printf("numbers[%d] = %d\n", i, numbers[i]);
    }

    printf("\nAccessing array using pointer arithmetic:\n");
    for (int i = 0; i < 5; i++) {
        printf("*(ptr + %d) = %d\n", i, *(ptr + i));
    }

    printf("\nModifying array elements using pointers:\n");
    for (int i = 0; i < 5; i++) {
        *(ptr + i) = *(ptr + i) + 1; // Increment each element by 1
        printf("numbers[%d] after increment = %d\n", i, numbers[i]);
    }

    return 0;
}

War alles klar?

Danke für Ihr Feedback!

Abschnitt 2. Kapitel 1