In C/C++, why might you define a struct (structure) type at global scope rather than repeating its definition inside each function that uses it?

Introduction / Context:
Choosing where to place a type definition in C or C++ affects code reuse, compilation dependencies, and interface design. Structures (struct) often represent common data across multiple translation units or functions. Placing a struct definition in a common, global scope (typically a header) avoids duplication and keeps declarations consistent throughout the program.

Given Data / Assumptions:

• The struct type is referenced by multiple functions or source files.
• We prefer a single authoritative definition to avoid copy-paste errors.
• Standard C/C++ compilation and separate header/source organization apply.

Concept / Approach:
Defining a struct once at global scope (commonly in a header included by all users) ensures a single source of truth. This avoids redundant definitions and linkage issues. It is not true that global definition implies the type will never change, nor is it a language requirement; it is a pragmatic design choice to improve maintainability and prevent ODR or redefinition errors across functions and files.

Step-by-Step Solution:
Identify that multiple functions need the same struct type.Place the struct definition in a shared header (global scope) and include it where needed.Benefit: compilation units share one consistent definition, reducing duplicate code and potential mismatches.Result: fewer lines of code and improved maintainability.

Verification / Alternative check:
Create two source files that use the same struct. If you maintain separate local definitions, a later change risks inconsistencies. With a single global definition in a header, both files compile against the same layout.

Why Other Options Are Wrong:

• You will never change its definition: Not guaranteed; types evolve.
• It is required in C++: Untrue; the language does not require global placement.
• All of the above: Incorrect because the other statements are false.

Common Pitfalls:
Placing full definitions in multiple headers without include guards can cause redefinition errors. Use include guards or #pragma once and expose only what is necessary.

Final Answer:
you save many lines of code by not rewriting an identical structure definition in each function that uses it.