Passing Arrays to Functions in C Using Pointers

In C, arrays can be passed to functions in two ways: by value and by reference. Passing an array by value means that a copy of the entire array is made and passed to the function. This can be inefficient, especially if the array is large. Passing an array by reference means that the address of the first element of the array is passed to the function. This allows the function to access the original array without making a copy.

One way to pass an array by reference to a function in C is to use pointers. A pointer is a variable that stores the address of another variable. When an array is passed to a function using a pointer, the pointer stores the address of the first element of the array. The function can then use this pointer to access any element of the array.

Here is an example of how to pass an array to a function using a pointer in C:

#include <stdio.h>

void print_array(int *arr, int size) {
  for (int i = 0; i < size; i++) {
    printf("%d\n", arr[i]);
  }
}

int main() {
  int arr[] = {1, 2, 3, 4, 5};
  int size = sizeof(arr) / sizeof(arr[0]);

  print_array(arr, size);

  return 0;
}

In this example, the function print_array() takes two arguments: a pointer to an array of integers, and the size of the array. The function iterates through the array and prints the value of each element.

The first argument to the function, arr, is a pointer to the first element of the array. The * symbol in front of the variable name indicates that it is a pointer. The size argument is the number of elements in the array.

The function print_array() can access any element of the array by using the pointer arr. For example, to print the value of the first element of the array, the function would use the following code:

printf("%d\n", *arr);

This code first dereferences the pointer arr. This means that the address stored in the pointer is converted to the value of the variable that it points to. In this case, the value of arr is the address of the first element of the array. The * symbol in front of arr tells the compiler to dereference the pointer.

After the pointer is dereferenced, the value of the first element of the array is printed to the console.

Passing arrays to functions using pointers is a powerful technique that can be used to improve the efficiency of your code. By passing an array by reference, you can avoid making a copy of the entire array, which can save memory and time.

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