gofmt is Go’s built-in source formatter. It parses Go code and rewrites it with consistent indentation, spacing, and alignment, producing one standard layout regardless of the programmer’s preferences. section 1.6 section 2.4.4
The design deliberately removes configuration and style debates. Standard formatting lowers the cognitive load of reading unfamiliar code and makes formatting a shared engineering convention rather than a review topic. section 1.6 section 2.4.4
Use gofmt in two practical modes:
- Run `gofmt -d main.go` to inspect a diff without changing the file. section 2.4.4
- Run `gofmt -w main.go` to rewrite the file in place. section 2.4.4
- Let an editor or IDE invoke gofmt on save, then use the diff mode when checking whether formatting is already standard. section 2.4.4
Checking a Go file
Given a file named `main.go`, run `gofmt -d main.go`. No output means the file already matches the standard format. A diff identifies changes such as indentation and spacing before any rewrite is applied. section 2.4.4
Listing 2.6 Testing your formatting with gofmt
$ gofmt -d main.go
Inspect the command used to test whether `main.go` follows standard Go formatting. section 2.4.4
