CS50 2024 | Arrays (Aula 2) - Curso de Introdução à Ciência da Computação de Harvard

Introduction

This tutorial is designed to provide a comprehensive overview of arrays in the C programming language, as covered in the CS50 course from Harvard. By the end of this guide, you will have a clearer understanding of how to utilize arrays for efficient data management and manipulation in your coding projects.

Step 1: Understanding Arrays

• Definition: An array is a collection of elements identified by index or key. In C, arrays are used to store multiple values in a single variable.
• Purpose: Arrays help to organize data efficiently, making it easier to perform operations on multiple items.
• Declaration: To declare an array in C, use the following syntax:

  type arrayName[arraySize];
  

  For example:

  int numbers[5];
  

Step 2: Initializing Arrays

• Static Initialization: You can initialize an array at the time of declaration:

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

• Dynamic Initialization: Arrays can also be initialized dynamically, for example, by using loops:

  for (int i = 0; i < 5; i++) {
      numbers[i] = i + 1;
  }
  

Step 3: Accessing Array Elements

• Indexing: Access elements in an array using their index, starting from 0:

  int firstNumber = numbers[0]; // Accesses the first element
  

• Looping Through Arrays: Use a loop to access and manipulate each element:

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

Step 4: Common Operations on Arrays

• Finding the Length: In C, you can find the length of an array as follows:

  int length = sizeof(numbers) / sizeof(numbers[0]);
  

• Searching: Implement a simple linear search to find an element:

  int search(int array[], int length, int target) {
      for (int i = 0; i < length; i++) {
          if (array[i] == target) {
              return i; // Return the index of the target
          }
      }
      return -1; // Not found
  }
  

Step 5: Multidimensional Arrays

• Definition: Multidimensional arrays are arrays of arrays, allowing storage of data in a matrix format.
• Declaration: Declare a 2D array like this:

  int matrix[3][3]; // A 3x3 matrix
  

• Accessing Elements: Access elements using two indices:

  matrix[0][0] = 1; // Set the first element
  

Practical Tips

• Memory Management: Be cautious about the size of arrays, as large arrays can lead to memory issues.
• Bounds Checking: Always ensure you do not access elements outside the defined array size to prevent undefined behavior.
• Use of Functions: Modularize your code by creating functions for common array operations like searching or sorting.

Conclusion

Understanding arrays is crucial for efficient programming in C. They allow you to manage multiple data points effectively and can be combined with functions to perform complex operations. As next steps, try implementing different types of arrays and practice writing functions that manipulate them. This foundational knowledge will greatly enhance your programming skills in the CS50 course and beyond.