Array Declaration

• C:

  • Arrays MUST HAVE a fixed size at the time of declaration.
  • The size is specified in square brackets.
  • The type of elements is specified.

  int myArray[4];  // Declares an array of 4 integers
  
  

• JavaScript:

  • Arrays are dynamic and can grow or shrink in size.
  • No need to specify the size or type of elements.

  let myArray = [];  // Declares an empty array
  
  

Element Access

• C:

  • Access elements using zero-based indexing.
  • The array name is a pointer to the first element.

  myArray[0] = 10;  // Sets the first element to 10
  int firstElement = myArray[0];  // Gets the first element
  
  

• JavaScript:

  • Access elements using zero-based indexing.

  myArray[0] = 10;  // Sets the first element to 10
  let firstElement = myArray[0];  // Gets the first element
  
  

Initialization

• C:

  • Arrays can be initialized at the time of declaration.
  • IF not all elements are initialized, the remaining elements are zero-initialized.

  int myArray[4] = {42, 39, 16, 7};  // Initializes the array with specific values
  

• JavaScript:

  • Arrays can be initialized with values at the time of declaration.

  let myArray = [42, 39, 16, 7];  // Initializes the array with specific values
  

Dynamic Resizing

• C:

  • Arrays have a fixed size. TO resize, you MUST allocate a new array and copy elements over.

  int *newArray = malloc(newSize * sizeof(int));
  memcpy(newArray, oldArray, oldSize * sizeof(int));
  free(oldArray);
  oldArray = newArray;
  

• JavaScript:

  • Arrays are dynamic and can be resized automatically.

  myArray.push(5);  // Adds an element to the end of the array
  

Type Safety

• C:

  • Arrays are strongly typed. ALL elements MUST be of the same type.

  int myArray[4];  // All elements must be integers
  

• JavaScript:

  • Arrays are loosely typed. Elements can be of different types.

  let myArray = [42, 'hello', true];  // Elements can be of different types
  

Bounds Checking

• C:

  • NO automatic bounds checking. Accessing out-of-bounds elements leads to undefined behavior.

  int x = myArray[5];  // Undefined behavior if myArray has less than 6 elements
  

• JavaScript:

  • Accessing out-of-bounds elements returns undefined without throwing an error.

  let x = myArray[5];  // Returns undefined if myArray has less than 6 elements
  

Memory Management

• C:

  • Memory management is manual. You MUST allocate and free memory yourself.

  int *myArray = malloc(10 * sizeof(int));  // Allocate memory for 10 integers
  free(myArray);  // Free the allocated memory