Package scope rules in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is package scope in Go?

Package scope means that a variable, function, or type is accessible anywhere within the same package but not outside it.

beginner

How do you make a function or variable accessible outside its package in Go?

By starting its name with an uppercase letter, making it exported and accessible from other packages.

beginner

Given this code snippet, where is the variable accessible?

package main

var count int = 5

func main() {
    // ...
}

The variable 'count' is accessible anywhere inside the 'main' package but not from other packages.

intermediate

What happens if two files in the same package declare variables with the same name at package scope?

It causes a compile-time error because package scope variables must have unique names within the package.

intermediate

Explain the difference between package scope and block scope in Go.

Package scope means the identifier is visible throughout the entire package, across all files. Block scope means the identifier is only visible within the enclosing block where it is declared (e.g., inside a function or if statement).

In Go, how do you make a variable accessible outside its package?

A Start its name with an uppercase letter

B Declare it inside the main function

C Use the 'public' keyword

D Prefix it with 'export_'

In Go, identifiers starting with uppercase letters are exported and accessible outside their package.

Where can a package-scoped variable be accessed?

A Only inside the function where it is declared

B Anywhere in the program

C Anywhere inside the same package

D Only inside the file where it is declared

Package scope means the variable is accessible anywhere within the same package.

What happens if two package-scoped variables have the same name in the same package?

A No problem, both exist separately

B Compile-time error

C The second variable overwrites the first

D Runtime error

Go does not allow duplicate package-scoped variable names in the same package; it causes a compile-time error.

Which of these is NOT true about package scope in Go?

A Unexported identifiers are only accessible inside the package

B Package scope variables are accessible across all files in the package

C Exported identifiers are accessible outside the package

D Package scope variables are accessible from other packages by default

Unexported package scope variables are NOT accessible from other packages.

If a variable name starts with a lowercase letter, what is its visibility in Go?

A Visible only inside its package

B Visible everywhere in the program

C Visible only inside its function

D Visible only inside its file

Lowercase names are unexported and visible only inside their package.

Describe how package scope works in Go and how it affects variable and function visibility.

Think about uppercase vs lowercase naming.

Explain why two package-scoped variables cannot have the same name in Go and what error occurs if they do.

Consider how Go enforces uniqueness in package scope.