Metadata

ID: go-best-practices/omit-default-slice-index

Language: Go

Severity: Warning

Category: Best Practices

Description

In Go, the expression s[n:len(s)] is used to slice a string or slice s starting from index n up to the end of s. However, it is considered suboptimal and can be replaced with the simpler and more expressive s[n:] notation.

Using s[n:len(s)] is not optimal for a few reasons:

1. Readability: The s[n:] notation provides a clearer and more concise representation of slicing from index n to the end of s. It eliminates the need to explicitly specify len(s), making the code more readable.
2. Simplicity: By using s[n:], you remove unnecessary redundancy in the code. It improves the simplicity of your code and reduces the chances of introducing errors when manually specifying the length of s.
3. Performance: Although the performance difference may be negligible, using s[n:] is more efficient than creating a len(s) expression. The s[n:] notation directly references the underlying slice without requiring an additional length calculation.

For example, let’s consider the following code snippets:

s := "Hello, World!"
fmt.Println(s[7:len(s)])

Output: “World!”

s := "Hello, World!"
fmt.Println(s[7:])

Output: “World!”

Both snippets will produce the same output, but the second one using s[7:] is preferred for its simplicity and readability.

By replacing s[n:len(s)] with s[n:], you can improve the clarity and maintainability of your code while still achieving the desired slicing functionality.

Non-Compliant Code Examples

func main() {
    d := s[n:len(s)]
}

Compliant Code Examples

func main() {
    d := s[n:]
}

func main() {
    d := s[n:len(s):len(s)]
}

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