fmt

Documentation

Index

• func Errorf(format string, a ...interface{}) error
• func Fprint(w io.Writer, a ...interface{}) (n int, err error)
• func Fprintf(w io.Writer, format string, a ...interface{}) (n int, err error)
• func Fprintln(w io.Writer, a ...interface{}) (n int, err error)
• func Print(a ...interface{}) (n int, err error)
• func Printf(format string, a ...interface{}) (n int, err error)
• func Println(a ...interface{}) (n int, err error)
• func Sprint(a ...interface{}) string
• func Sprintf(format string, a ...interface{}) string
• func Sprintln(a ...interface{}) string
• type Formatter
• type GoStringer
• type State
• type Stringer

Functions

func Errorf

func Errorf(format string, a ...interface{}) error

Errorf formats according to a format specifier and returns the string as a value that satisfies error.

If the format specifier includes a %w verb with an error operand, the returned error will implement an Unwrap method returning the operand. It is invalid to include more than one %w verb or to supply it with an operand that does not implement the error interface. The %w verb is otherwise a synonym for %v.

func Fprint

func Fprint(w io.Writer, a ...interface{}) (n int, err error)

Fprint formats using the default formats for its operands and writes to w. Spaces are added between operands when neither is a string. It returns the number of bytes written and any write error encountered.

func Fprintf

func Fprintf(w io.Writer, format string, a ...interface{}) (n int, err error)

Fprintf formats according to a format specifier and writes to w. It returns the number of bytes written and any write error encountered.

func Fprintln

func Fprintln(w io.Writer, a ...interface{}) (n int, err error)

Fprintln formats using the default formats for its operands and writes to w. Spaces are always added between operands and a newline is appended. It returns the number of bytes written and any write error encountered.

func Print

func Print(a ...interface{}) (n int, err error)

Print formats using the default formats for its operands and writes to standard output. Spaces are added between operands when neither is a string. It returns the number of bytes written and any write error encountered.

func Printf

func Printf(format string, a ...interface{}) (n int, err error)

Printf formats according to a format specifier and writes to standard output. It returns the number of bytes written and any write error encountered.

func Println

func Println(a ...interface{}) (n int, err error)

Println formats using the default formats for its operands and writes to standard output. Spaces are always added between operands and a newline is appended. It returns the number of bytes written and any write error encountered.

func Sprint

func Sprint(a ...interface{}) string

Sprint formats using the default formats for its operands and returns the resulting string. Spaces are added between operands when neither is a string.

func Sprintf

func Sprintf(format string, a ...interface{}) string

Sprintf formats according to a format specifier and returns the resulting string.

func Sprintln

func Sprintln(a ...interface{}) string

Sprintln formats using the default formats for its operands and returns the resulting string. Spaces are always added between operands and a newline is appended.

Types

type Formatter

type Formatter interface {
	Format(f State, verb rune)
}

Formatter is implemented by any value that has a Format method. The implementation controls how State and rune are interpreted, and may call Sprint(f) or Fprint(f) etc. to generate its output.

type GoStringer

type GoStringer interface {
	GoString() string
}

GoStringer is implemented by any value that has a GoString method, which defines the Go syntax for that value. The GoString method is used to print values passed as an operand to a %#v format.

type State

type State interface {
	// Write is the function to call to emit formatted output to be printed.
	Write(b []byte) (n int, err error)
	// Width returns the value of the width option and whether it has been set.
	Width() (wid int, ok bool)
	// Precision returns the value of the precision option and whether it has been set.
	Precision() (prec int, ok bool)

	// Flag reports whether the flag c, a character, has been set.
	Flag(c int) bool
}

State represents the printer state passed to custom formatters. It provides access to the io.Writer interface plus information about the flags and options for the operand's format specifier.

type Stringer

type Stringer interface {
	String() string
}

Stringer is implemented by any value 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.