What is the Purpose of the Underscore Comma ('_,') in Go Declarations?

Understanding the Role of "_,” in Go Declarations

In Go, the underscore comma ("_,") is commonly used in variable declarations when you don't intend to use all the values returned by a function. It's known as the "blank identifier" and plays a significant role in avoiding unnecessary variable declarations.

Consider the following code snippet:

_, prs := m["example"]

Here, the blank identifier ("_") is used to ignore the return value of the index operation m["example"]. This is because the declaration is interested only in the second return value, represented by prs, which indicates whether the key exists in the map or not.

If you were to declare the variable directly, as shown below:

prs := m["example"]

Go would complain about the unused variable on the left side of the assignment. The "blank identifier" allows you to sidestep this issue and focus on the value you actually require.

Another use case of the "_," syntax is in loop statements, where you may only need one or some of the returned values. Consider the following example:

sum := 0
for _, value := range array {
    sum += value
}

In this code, the loop iterates over the array, discarding the index (first return value) and using the underscore to represent the currently iterated element (second return value), which is stored in the variable value.

The "blank identifier" also finds its way into import statements in Go, allowing you to import packages without explicitly using their functions or types.

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