OutOfBounds

Out of bounds (often written as out-of-bounds) is a general term used to describe data, objects, or events that lie outside defined boundaries or limits. The concept appears in multiple domains, including computing, sports, and mathematics, and its precise definition depends on the context.

In computing, out-of-bounds typically refers to accessing elements outside the valid range of a data structure such as an array, list, or buffer. Such access can trigger runtime errors, undefined behavior, or security vulnerabilities. Languages with automatic bounds checking, like Java or Python, usually raise a specific exception (for example, ArrayIndexOutOfBoundsException or IndexError) when an illegal index is accessed. Lower-level languages such as C and C++ may experience memory safety issues or segmentation faults if bounds are violated, unless careful precautions are taken. Out-of-bounds reads can leak data, while out-of-bounds writes can corrupt memory or overwrite adjacent data. Defensive programming practices—such as bounds checks, safe containers, and bounds-aware algorithms—help mitigate these risks.

In sports and games, out of bounds describes the situation where the ball, equipment, or a player has crossed the boundary lines of the playing area. The result typically stops play, and possession or restart rules determine the next action. Boundary definitions vary by sport and competition, but the core concept remains the same: events occurring outside the defined field of play are considered out of bounds.

Common related concepts include off-by-one errors in programming, boundary conditions in numerical methods, and boundary enforcement in user interfaces. Understanding and managing out-of-bounds conditions is important for correctness, safety, and reliability across disciplines.