Why is my function in a separate Go package undefined?

Function in Separate Package Undefined

In the given code structure, a function defined in a separate lib.go file is not recognized as defined when called from the main.go file. Let's explore the issue and find a solution.

When attempting to compile main.go with go build main.go, the error "undefined: Test" is encountered. This is because the Test function is defined in lib.go, which is in a different package (named "main") than main.go.

In Go, packages are isolated namespaces, and functions defined in one package cannot be directly accessed by functions in another package without explicit imports. To resolve this issue, you can do either of the following:

• Use a more specific import statement: In main.go, import the lib package by adding import "packagetest/lib" at the beginning of the file.
• Use the full package path: In main.go, replace Test() with packagetest.lib.Test() to explicitly indicate the full package path where the Test function is defined.
• Build the entire project: Instead of go build main.go, run go build at the project root to build all the necessary files. This will allow the compiler to find and import the lib.go file.

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