what would happen if a program tried to access a variable that was defined locally in another part of the program?

what would happen if a program tried to access a variable that was defined locally in another part of the program?

3 hours ago 2
Nature

If a program tries to access a variable that was defined locally in another part of the program (such as inside a different function or block), it will generally result in an error or failure to access that variable. This is because local variables have a limited scope, meaning they are only accessible within the function or block where they are defined.

Explanation of Variable Scope

  • Local variables are created within a function or block and only exist during the execution of that function or block. Once the function exits, the local variable ceases to exist and cannot be accessed outside
  • Trying to access a local variable from outside its defining function or block usually causes a compilation error or runtime error, depending on the language. For example, in C, attempting to use a local variable outside its function results in a compilation error because the variable is not known there
  • In languages with lexical (static) scope, a variable's scope is limited to the block or function where it is declared, so other functions cannot see or use it
  • In Python, accessing a local variable from another function leads to a NameError because the variable is not defined in the global scope or the calling function's scope
  • Global variables, by contrast, are accessible from anywhere in the program, which is why variables defined outside functions can be accessed inside functions unless shadowed by a local variable

Summary

  • If a program tries to access a variable defined locally in another part of the program, it will not be able to access it due to scope restrictions.
  • This results in errors such as compilation errors in compiled languages (e.g., C) or runtime errors like NameError in interpreted languages (e.g., Python).
  • To share data between parts of a program, variables must be declared with a broader scope (e.g., global scope) or passed explicitly as parameters.

This behavior enforces modularity and prevents unintended side effects by restricting variable visibility to where it is logically relevant

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