Using arrays and strings in C programs!

1. Program with Functionality of Character Arrays:
2. Other Ways to Use Arrays in C:
3. Considerations for Arrays in C:

1.) Program with Functionality of Character Arrays:

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

#define DISPLAY 1 // Change this to 1 to see the output

int main() {
  char name[] = "Reinhold Messner"; // Arrays can have different data types, not just char. They can be int, double, or custom types.

  int numbers[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}; // int, double, and other data types differ from char in that they do NOT have a NULL-terminator. Note the slightly different declaration.

  // First, let's prove that the length of "name" is 7 elements.
  // The function "strlen()" returns the length of a character string.
  printf("Length of name[] = %d\n\n\n", strlen(name));

  // When you run this program, you will notice that 16 is printed. BUT I THOUGHT YOU SAID THE LENGTH OF name IS 7 ELEMENTS?!?!?!

  // Change the above code so that the first line looks like this:
  // char name[16] = "Reinhold Messner";

  /*
  Reinhold Messner has 16 letters, so that should work, right?
  You will find that this leads to undefined results. It might not compile, or it might display the length of "Reinhold Messner" as 162 (or some other number). It is entirely dependent on the operating system. The reason for this is that changing to "char name[16] = "Reinhold Messner"" only reserves 16 elements in the array. There is no space for the NULL-terminating character, which MUST ALWAYS be present in character arrays. So, make a mental note: "strlen()" returns the length of a character string (character array), excluding the NULL-terminator.
  */

  // Remember to set "DISPLAY" to 1 to see what is printed, but you should first note it down on paper :)

  if (DISPLAY) {
      printf("%s\n", name);
      printf("%c\n\n", name[3]);
  }

  name[3] = name[2];

  if (DISPLAY)
      printf("%s\n\n", name);

  name[5] = "t";

  if (DISPLAY)
      printf("%s\n\n", name);

  name[3] = "\0'; // '\0" represents NULL

  if (DISPLAY)
      printf("%s\n\n", name);

  // Now print a value from the integer array

  printf("numbers[2] = %d\n", numbers[2]);

  if (DISPLAY)
      printf("%p\n", (void*)numbers);

  // What do you think this does? Arrays are low-level contiguous memory blocks of a certain length. This statement prints the memory address where the first element of "numbers" is stored.

  return EXIT_SUCCESS;

  // EXIT_SUCCESS is a predefined constant that tells the operating system that this program had no issues during execution. ** NOTE ** It is defined as 0, so you might see "return 0;" instead.
}

2.) Other Ways to Use Arrays in C:

// A one-dimensional array: This is the basic array that stores a collection of elements of the same data type. For example, an array of integers:

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

// A multidimensional array: These are arrays organized in the form of matrices or tables. For example, a 2D matrix:

int matrix[3][3] = {
  {1, 2, 3},
  {4, 5, 6},
  {7, 8, 9}
};

// A character array (string): Character arrays are often used to store strings. They are null-terminated, meaning they end with a null-terminating character "\0". For example:

char name[] = "John";

// Arrays of character arrays (array of strings): This is commonly used to store a collection of strings, e.g., an array of names:

char names[3][20] = {"Alice", "Bob", "Charlie"};

// An array of pointers: This allows storing pointers to different data types in an array. For example, an array of integer pointers:

int *ptrArray[3];

// Dynamic arrays: These are created at runtime using malloc or calloc from heap memory. This type of array allows flexible size management. For example:

int *dynamicArray = (int*)malloc(5 * sizeof(int));

// Arrays of structures: You can create arrays of custom structures to store complex data structures. For example, a structure for student information:

struct Student {
  char name[50];
  int age;
};

struct Student students[3];

// Constant arrays: You can declare arrays containing constants and computed at compile-time:

const int fib[10] = {1, 1, 2, 3, 5, 8, 13, 21, 34, 55};

// These are just a few examples of how arrays can be used in C. The choice of the right array type depends on the requirements of your application.

3.) Considerations for Arrays in C: