69、Extern Declaration in C and C++

Extern Declaration in C and C++

1. Introduction to Extern

In C and C++ programming, the extern keyword plays a crucial role in managing variables and functions across multiple source files. It allows developers to declare external symbols that are defined elsewhere in the program. This ensures that variables and functions can be shared and accessed across different modules without duplication. Understanding how to properly use extern is essential for writing modular and maintainable code.

1.1 Purpose of Extern

The primary purpose of the extern keyword is to inform the compiler that a particular variable or function is defined outside the current file. This enables the linker to resolve the symbol