How to use the command gofmt (with examples)

The gofmt command is a tool for formatting Go source code. It provides a simple way to automatically format Go code in a consistent and readable manner. By using gofmt, developers can ensure that their code follows the Go formatting style guide, making it easier to read and maintain.

Use case 1: Format a file and display the result to the console

Code:

gofmt source.go

Motivation:

When working on a Go project, it is important to ensure that the code follows the standard formatting guidelines. By running gofmt source.go, the command will format the source.go file according to the Go style guide and display the formatted code in the console. This allows developers to quickly see how their code would look after formatting, without modifying the original file.

Explanation:

• gofmt is the command itself.
• source.go is the name of the file that needs to be formatted.

Example output:

The command will output the formatted code to the console.

Use case 2: Format a file, overwriting the original file in-place

Code:

gofmt -w source.go

Motivation:

In some cases, developers might want to apply the formatting changes directly to the original file. This is useful when making the formatting changes a permanent part of the codebase, ensuring that all future edits will follow the same formatting conventions.

Explanation:

• gofmt is the command itself.
• -w is an argument that tells gofmt to overwrite the original file.
• source.go is the name of the file that needs to be formatted.

Example output:

The file source.go will be updated with the formatted code.

Use case 3: Format a file, and then simplify the code, overwriting the original file

Code:

gofmt -s -w source.go

Motivation:

In addition to formatting the code, gofmt can also perform additional simplifications, making the code shorter and potentially more efficient. By using the -s option in conjunction with -w, developers can apply these simplifications to the code and overwrite the original file.

Explanation:

• gofmt is the command itself.
• -s is an argument that tells gofmt to simplify the code in addition to formatting it.
• -w is an argument that tells gofmt to overwrite the original file.
• source.go is the name of the file that needs to be formatted.

Example output:

The file source.go will be updated with the formatted and simplified code.

Use case 4: Print all (including spurious) errors

Code:

gofmt -e source.go

Motivation:

When running gofmt, it can sometimes be useful to see all the errors, including any spurious ones. This can help identify potential issues in the code that may not have been caught by the compiler.

Explanation:

• gofmt is the command itself.
• -e is an argument that tells gofmt to print all errors, including spurious ones.
• source.go is the name of the file that needs to be formatted.

Example output:

The command will output all the errors encountered during the formatting process, including any spurious errors.