Go Package fmt: Difference between revisions

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==<tt>%+v</tt>==
==<tt>%+v</tt>==
When printing structs, the plus flag <code>%+v</code> adds field names.


=Functions=
=Functions=

Revision as of 21:50, 22 December 2023

External

Internal

Formatting

Leading Zero Padding for Integers

i := 7
s := fmt.Sprintf("%06d", i) // will produce "000007" (five zeroes)

Leading Space Padding for Integer

i := 7
s := fmt.Sprintf("%6d", i) // will produce "     7" (five spaces)

%v

Print the value in the default format.

%+v

When printing structs, the plus flag %+v adds field names.

Functions

Sprintf()

Format a string and returns it as a result:

message := fmt.Sprintf("Hi, %v. Welcome!", name)

For more details on the format string, see:

Printf() Format String

Printf(), Println()

Printing to stdout and stderr

Scanf(), Scanln()

Handling stdin in Go

Errorf()

Error Handling | Wrapping Errors

Interfaces

fmt.Stringer

type Stringer interface {
  String() string
}

Stringer is implemented by any type that has a String() method, which defines the "native" format for that value. The String() method is used to print values passed as an operand to any format that accepts a string or to an unformatted printer such as Print. For a usage example, see:

The Equivalent of Java toString() in Go