Why Can't I Assign a Value to a Variable Outside of a Function in Go?

Non-Declaration Statement Outside Function Body in Go

In Go, it's not possible to declare variables outside of functions using a non-declaration statement. This error occurs when trying to assign a value to a non-declared variable, as seen in the following example:

Solution

To declare a globally-accessible variable in Go, use the var keyword outside of the main function. The variable's name should start with a lowercase letter to make it package-private (only accessible within its package).

This method allows you to declare a variable outside of a function and change its value within functions in the same package.

Additional Information

• The := short declaration syntax is only allowed within function bodies.
• Variables declared with var can be of any type, including non-primitive types like maps and structs.
• Go also provides the init function, which is called before the main function and can be used for package initialization.

Sample Code

Here's an example of how to use a package-private variable and change its value:

In this example, the sessionID variable is accessible from anywhere within the apitest package. It's initialized to an empty string in the main function and updated within the updateSessionID function.

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