C++ Variable Scope: Differences Between Local and Global Variables

This article analyzes the scope of C++ variables and the core differences between local and global variables. The scope of a variable determines its access range, which is divided into two categories: local and global. Local variables are defined within a function or code block and are limited to that scope. They are created when the function is called and destroyed when the function execution ends. Local variables have a random default value (unsafe). They are suitable for small - range independent data and are safe because they are only visible locally. Global variables are defined outside all functions and have a scope that covers the entire program. Their lifecycle spans the entire program execution. For basic data types, global variables have a default value of 0. They are easily modified by multiple functions. They are suitable for sharing data but require careful use. The core differences are as follows: local variables have a small scope, a short lifecycle, and a random default value; global variables have a large scope, a long lifecycle, and a default value of 0. It is recommended to prioritize using local variables. If global variables are used, they should be set as const to prevent modification, which can improve code stability. Understanding variable scope helps in writing robust code.