Dimension

Tags: #◇CCPROG2 #◇C Programming #◇Programming #◇Computer Science #◇Data Structures #◇Data Types #◇Structured Programming #◇Memory Management

◇Overview

The dimension of an array refers to the number of indices needed to access an element.

◇Key Concepts

1D arrays: single index — arr[i] 2D arrays: two indices — arr[i][j] 3D+ arrays: three or more indices Higher dimensions map to contiguous memory in row-major order

◇Details / Theory

One-Dimensional (1D)

A simple list of elements. Access: arr[i].

『』

int arr[5] = {10, 20, 30, 40, 50};

Two-Dimensional (2D)

Think of it as a table (rows × columns). Access: arr[row][col].

『』

int matrix[3][4];  // 3 rows, 4 columns
matrix[0][0] = 1;  // First element
matrix[2][3] = 12; // Last element

Three-Dimensional and Beyond

Used for more complex data (e.g., 3D grids, RGB images).

『』

int cube[2][3][4];  // 2 layers, 3 rows, 4 columns per layer

Memory Layout

All multi-dimensional arrays are stored as contiguous 1D blocks in row-major order in C:
arr[0][0], arr[0][1], ..., arr[0][n-1], arr[1][0], ...

◇Common Pitfalls

Confusing row and column order in 2D arrays. Excessive dimensions make code hard to read — rarely need more than 3D.

◇Summary

TL;DR — Array dimension = number of indices needed to access an element. C supports 1D, 2D, 3D, and higher-dimensional arrays, all stored contiguously in row-major order.

◇Links

Previous Topic: ◇Element Type
Next Topic: ◇Size
Related Notes: ◇Characteristics & Attributes, ◇Dimensions of Arrays

DIMENSION