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 Fscan(r io.Reader, a ...interface{}) (n int, err error)
• func Fscanf(r io.Reader, format string, a ...interface{}) (n int, err error)
• func Fscanln(r io.Reader, 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 Scan(a ...interface{}) (n int, err error)
• func Scanf(format string, a ...interface{}) (n int, err error)
• func Scanln(a ...interface{}) (n int, err error)
• func Sprint(a ...interface{}) string
• func Sprintf(format string, a ...interface{}) string
• func Sprintln(a ...interface{}) string
• func Sscan(str string, a ...interface{}) (n int, err error)
• func Sscanf(str string, format string, a ...interface{}) (n int, err error)
• func Sscanln(str string, a ...interface{}) (n int, err error)
• type Formatter
• type GoStringer
• type ScanState
• type Scanner
• 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.

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 Fscan

func Fscan(r io.Reader, a ...interface{}) (n int, err error)

Fscan scans text read from r, storing successive space-separated values into successive arguments. Newlines count as space. It returns the number of items successfully scanned. If that is less than the number of arguments, err will report why.

func Fscanf

func Fscanf(r io.Reader, format string, a ...interface{}) (n int, err error)

Fscanf scans text read from r, storing successive space-separated values into successive arguments as determined by the format. It returns the number of items successfully parsed.

func Fscanln

func Fscanln(r io.Reader, a ...interface{}) (n int, err error)

Fscanln is similar to Fscan, but stops scanning at a newline and after the final item there must be a newline or EOF.

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 Scan

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

Scan scans text read from standard input, storing successive space-separated values into successive arguments. Newlines count as space. It returns the number of items successfully scanned. If that is less than the number of arguments, err will report why.

func Scanf

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

Scanf scans text read from standard input, storing successive space-separated values into successive arguments as determined by the format. It returns the number of items successfully scanned.

func Scanln

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

Scanln is similar to Scan, but stops scanning at a newline and after the final item there must be a newline or EOF.

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.

func Sscan

func Sscan(str string, a ...interface{}) (n int, err error)

Sscan scans the argument string, storing successive space-separated values into successive arguments. Newlines count as space. It returns the number of items successfully scanned. If that is less than the number of arguments, err will report why.

func Sscanf

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

Sscanf scans the argument string, storing successive space-separated values into successive arguments as determined by the format. It returns the number of items successfully parsed.

func Sscanln

func Sscanln(str string, a ...interface{}) (n int, err error)

Sscanln is similar to Sscan, but stops scanning at a newline and after the final item there must be a newline or EOF.

Types

type Formatter

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

Formatter is the interface implemented by values with a custom formatter. The implementation of Format 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 ScanState

type ScanState interface {
	// ReadRune reads the next rune (Unicode code point) from the input.
	// If invoked during Scanln, Fscanln, or Sscanln, ReadRune() will
	// return EOF after returning the first '\n' or when reading beyond
	// the specified width.
	ReadRune() (r rune, size int, err error)
	// UnreadRune causes the next call to ReadRune to return the same rune.
	UnreadRune() error
	// SkipSpace skips space in the input. Newlines are treated as space
	// unless the scan operation is Scanln, Fscanln or Sscanln, in which case
	// a newline is treated as EOF.
	SkipSpace()
	// Token skips space in the input if skipSpace is true, then returns the
	// run of Unicode code points c satisfying f(c).  If f is nil,
	// !unicode.IsSpace(c) is used; that is, the token will hold non-space
	// characters.  Newlines are treated as space unless the scan operation
	// is Scanln, Fscanln or Sscanln, in which case a newline is treated as
	// EOF.  The returned slice points to shared data that may be overwritten
	// by the next call to Token, a call to a Scan function using the ScanState
	// as input, or when the calling Scan method returns.
	Token(skipSpace bool, f func(rune) bool) (token []byte, err error)
	// Width returns the value of the width option and whether it has been set.
	// The unit is Unicode code points.
	Width() (wid int, ok bool)
	// Because ReadRune is implemented by the interface, Read should never be
	// called by the scanning routines and a valid implementation of
	// ScanState may choose always to return an error from Read.
	Read(buf []byte) (n int, err error)
}

ScanState represents the scanner state passed to custom scanners. Scanners may do rune-at-a-time scanning or ask the ScanState to discover the next space-delimited token.

type Scanner

type Scanner interface {
	Scan(state ScanState, verb rune) error
}

Scanner is implemented by any value that has a Scan method, which scans the input for the representation of a value and stores the result in the receiver, which must be a pointer to be useful. The Scan method is called for any argument to Scan, Scanf, or Scanln that implements it.

type State

type State interface {
	// Write is the function to call to emit formatted output to be printed.
	Write(b []byte) (ret 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 returns 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.