What does a blank identifier _ mean in Go?
Jul 12, 2025 am 02:06 AMIn Go, the blank identifier \_ is used to ignore unwanted values, such as function return values, import packages, or structure fields. The main uses include: 1. Ignore the return value of the function, such as value, \_ := someFunction(); 2. Ignore the key or value in the loop, such as for \_, value := range slice; 3. Avoid compilation errors that do not use imports or variables, such as import \_ "some/package" or \_ = x; 4. Used as a fill field in the structure, such as type MyStruct struct { A int \_ int B int }, thereby keeping the code concise and avoiding compilation errors.
In Go, a blank identifier _
is used to ignore values ??that are returned or not needed in a particular context. It's a way to tell the compiler, "I know there's a value here, but I don't care about using it." This comes in handy especially when you're dealing with multiple return values ??from functions, imports, or struct fields — and you only need some of them.

Ignoring Returned Values ??from Functions
One of the most common uses of _
is when you want to ignore one or more return values ??from a function.
For example, many functions in Go return both a value and an error:

value, _ := someFunction()
Here, if you're sure the function won't return an error (or you simply don't care about handling it at that point), you can use _
to skip assigning the error.
?? But be careful — ignoring errors like this can hide bugs or lead to unexpected behavior down the line. Use this pattern only when it makes sense, such as in quick scripts or when you're absolutely sure the operation won't fail.
You might also see it when looping over maps or slices where you only need the key or the value:

for _, value := range slice { fmt.Println(value) }
Or if you only need the index:
for index, _ := range slice { fmt.Println(index) }
This avoids having to declare and use unused variables, which would otherwise cause a compilation error in Go.
Avoiding Unused Import or Variable Errors
Go doesn't allow unused imports or variables. If you're importing a package just for its side effects (like initialization), you can use _
to prevent a "unused import" error:
import _ "some/package"
This tells Go you're importing the package on purpose, even though you're not referencing any of its exported names.
Same goes for variables — if you have a variable that you're not using temporarily during development:
func main() { x := 42 _ = x }
This keeps the code compiling without commenting out or deleting the variable entirely.
Using Blank Identifiers in Struct Fields (Less Common)
Blank identifiers can also be used in struct definitions to pad memory layout or avoid conflicts, although this is much less common and mostly seen in low-level code:
type MyStruct struct { A int _ int // padding field B int }
This skips assigning a name to the second integer while still reserved space in the struct.
So, in short:
- Use
_
to ignore return values ??or loop variables - Use it to import packages for initialization only
- Occasionally use it to handle unused variables or fields
It's a small feature but very useful for keeping your Go code clean and free of unnecessary variables.
The above is the detailed content of What does a blank identifier _ mean in Go?. For more information, please follow other related articles on the PHP Chinese website!

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