An array is a fundamental data structure that stores a collection of elements in contiguous memory locations. Think of it like a row of numbered mailboxes, where each mailbox can hold one piece of data. Arrays have three key characteristics: all elements are of the same data type, they have a fixed size in static arrays, and each element can be accessed directly using its index position.
Array indexing is the mechanism that allows us to access individual elements by their position. Most programming languages use zero-based indexing, meaning the first element is at index 0, the second at index 1, and so on. This direct access makes arrays very efficient for retrieving specific elements when you know their position.
Arrays support various operations that make them versatile data structures. Traversal allows us to visit each element sequentially. We can insert new elements or delete existing ones, though this may require shifting other elements. Search operations help us find specific values, and sorting arranges elements in a particular order. The efficiency of these operations depends on the specific implementation and the operation being performed.
Array structure is built on zero-based indexing, where elements are stored in contiguous memory locations. Each element can be accessed directly using its index in constant time. The memory address of any element can be calculated using the formula: base address plus index times element size. This structure makes arrays extremely efficient for random access operations, which is why they're fundamental to many algorithms and data structures.
Array operations have different time complexities based on their nature. Access and update operations are very fast with O(1) complexity since we can directly jump to any index. However, insertion and deletion operations typically require O(n) time because elements may need to be shifted to maintain the array structure. Search operations also take O(n) time in the worst case when we need to check every element. Understanding these complexities helps us choose the right data structure for specific tasks.
Arrays come in two main types: static and dynamic. Static arrays have a fixed size determined at declaration time, making them memory efficient with fast access but inflexible for changing data requirements. Dynamic arrays can resize during program execution, offering flexibility at the cost of additional memory overhead and potential performance impact during resizing operations. The choice between them depends on whether you know the data size in advance and need the flexibility to grow or shrink the array.