...

package main

import "fmt"

func main() {
	fmt.Println("Hello, 世界")
}

Run Format

Package strings

import "strings"

Overview ▹

Overview ▾

Package strings implements simple functions to manipulate UTF-8 encoded strings.

For information about UTF-8 strings in Go, see https://blog.golang.org/strings.

Index ▹

Index ▾

func Compare(a, b string) int

func Contains(s, substr string) bool

func ContainsAny(s, chars string) bool

func ContainsRune(s string, r rune) bool

func Count(s, sep string) int

func EqualFold(s, t string) bool

func Fields(s string) []string

func FieldsFunc(s string, f func(rune) bool) []string

func HasPrefix(s, prefix string) bool

func HasSuffix(s, suffix string) bool

func Index(s, sep string) int

func IndexAny(s, chars string) int

func IndexByte(s string, c byte) int

func IndexFunc(s string, f func(rune) bool) int

func IndexRune(s string, r rune) int

func Join(a []string, sep string) string

func LastIndex(s, sep string) int

func LastIndexAny(s, chars string) int

func LastIndexByte(s string, c byte) int

func LastIndexFunc(s string, f func(rune) bool) int

func Map(mapping func(rune) rune, s string) string

func Repeat(s string, count int) string

func Replace(s, old, new string, n int) string

func Split(s, sep string) []string

func SplitAfter(s, sep string) []string

func SplitAfterN(s, sep string, n int) []string

func SplitN(s, sep string, n int) []string

func Title(s string) string

func ToLower(s string) string

func ToLowerSpecial(_case unicode.SpecialCase, s string) string

func ToTitle(s string) string

func ToTitleSpecial(_case unicode.SpecialCase, s string) string

func ToUpper(s string) string

func ToUpperSpecial(_case unicode.SpecialCase, s string) string

func Trim(s string, cutset string) string

func TrimFunc(s string, f func(rune) bool) string

func TrimLeft(s string, cutset string) string

func TrimLeftFunc(s string, f func(rune) bool) string

func TrimPrefix(s, prefix string) string

func TrimRight(s string, cutset string) string

func TrimRightFunc(s string, f func(rune) bool) string

func TrimSpace(s string) string

func TrimSuffix(s, suffix string) string

func NewReader(s string) *Reader

func (r *Reader) Len() int

func (r *Reader) Read(b []byte) (n int, err error)

func (r *Reader) ReadAt(b []byte, off int64) (n int, err error)

func (r *Reader) ReadByte() (b byte, err error)

func (r *Reader) ReadRune() (ch rune, size int, err error)

func (r *Reader) Seek(offset int64, whence int) (int64, error)

func (r *Reader) Size() int64

func (r *Reader) UnreadByte() error

func (r *Reader) UnreadRune() error

func (r *Reader) WriteTo(w io.Writer) (n int64, err error)

func NewReplacer(oldnew ...string) *Replacer

func (r *Replacer) Replace(s string) string

func (r *Replacer) WriteString(w io.Writer, s string) (n int, err error)

Examples

Package files

compare.go reader.go replace.go search.go strings.go strings_amd64.go strings_decl.go

func Compare

func Compare(a, b string) int

Compare returns an integer comparing two strings lexicographically. The result will be 0 if a==b, -1 if a < b, and +1 if a > b.

Compare is included only for symmetry with package bytes. It is usually clearer and always faster to use the built-in string comparison operators ==, <, >, and so on.

func Contains

func Contains(s, substr string) bool

Contains reports whether substr is within s.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.Contains("seafood", "foo"))
	fmt.Println(strings.Contains("seafood", "bar"))
	fmt.Println(strings.Contains("seafood", ""))
	fmt.Println(strings.Contains("", ""))
}

true
false
true
true

Run Format

func ContainsAny

func ContainsAny(s, chars string) bool

ContainsAny reports whether any Unicode code points in chars are within s.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.ContainsAny("team", "i"))
	fmt.Println(strings.ContainsAny("failure", "u & i"))
	fmt.Println(strings.ContainsAny("foo", ""))
	fmt.Println(strings.ContainsAny("", ""))
}

false
true
false
false

Run Format

func ContainsRune

func ContainsRune(s string, r rune) bool

ContainsRune reports whether the Unicode code point r is within s.

func Count

func Count(s, sep string) int

Count counts the number of non-overlapping instances of sep in s. If sep is an empty string, Count returns 1 + the number of Unicode code points in s.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.Count("cheese", "e"))
	fmt.Println(strings.Count("five", "")) // before & after each rune
}

3
5

Run Format

func EqualFold

func EqualFold(s, t string) bool

EqualFold reports whether s and t, interpreted as UTF-8 strings, are equal under Unicode case-folding.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.EqualFold("Go", "go"))
}

true

Run Format

func Fields

func Fields(s string) []string

Fields splits the string s around each instance of one or more consecutive white space characters, as defined by unicode.IsSpace, returning an array of substrings of s or an empty list if s contains only white space.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Printf("Fields are: %q", strings.Fields("  foo bar  baz   "))
}

Fields are: ["foo" "bar" "baz"]

Run Format

func FieldsFunc

func FieldsFunc(s string, f func(rune) bool) []string

FieldsFunc splits the string s at each run of Unicode code points c satisfying f(c) and returns an array of slices of s. If all code points in s satisfy f(c) or the string is empty, an empty slice is returned. FieldsFunc makes no guarantees about the order in which it calls f(c). If f does not return consistent results for a given c, FieldsFunc may crash.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
	"unicode"
)

func main() {
	f := func(c rune) bool {
		return !unicode.IsLetter(c) && !unicode.IsNumber(c)
	}
	fmt.Printf("Fields are: %q", strings.FieldsFunc("  foo1;bar2,baz3...", f))
}

Fields are: ["foo1" "bar2" "baz3"]

Run Format

func HasPrefix

func HasPrefix(s, prefix string) bool

HasPrefix tests whether the string s begins with prefix.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.HasPrefix("Gopher", "Go"))
	fmt.Println(strings.HasPrefix("Gopher", "C"))
	fmt.Println(strings.HasPrefix("Gopher", ""))
}

true
false
true

Run Format

func HasSuffix

func HasSuffix(s, suffix string) bool

HasSuffix tests whether the string s ends with suffix.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.HasSuffix("Amigo", "go"))
	fmt.Println(strings.HasSuffix("Amigo", "O"))
	fmt.Println(strings.HasSuffix("Amigo", "Ami"))
	fmt.Println(strings.HasSuffix("Amigo", ""))
}

true
false
false
true

Run Format

func Index

func Index(s, sep string) int

Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.Index("chicken", "ken"))
	fmt.Println(strings.Index("chicken", "dmr"))
}

4
-1

Run Format

func IndexAny

func IndexAny(s, chars string) int

IndexAny returns the index of the first instance of any Unicode code point from chars in s, or -1 if no Unicode code point from chars is present in s.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.IndexAny("chicken", "aeiouy"))
	fmt.Println(strings.IndexAny("crwth", "aeiouy"))
}

2
-1

Run Format

func IndexByte

func IndexByte(s string, c byte) int

IndexByte returns the index of the first instance of c in s, or -1 if c is not present in s.

func IndexFunc

func IndexFunc(s string, f func(rune) bool) int

IndexFunc returns the index into s of the first Unicode code point satisfying f(c), or -1 if none do.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
	"unicode"
)

func main() {
	f := func(c rune) bool {
		return unicode.Is(unicode.Han, c)
	}
	fmt.Println(strings.IndexFunc("Hello, 世界", f))
	fmt.Println(strings.IndexFunc("Hello, world", f))
}

7
-1

Run Format

func IndexRune

func IndexRune(s string, r rune) int

IndexRune returns the index of the first instance of the Unicode code point r, or -1 if rune is not present in s.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.IndexRune("chicken", 'k'))
	fmt.Println(strings.IndexRune("chicken", 'd'))
}

4
-1

Run Format

func Join

func Join(a []string, sep string) string

Join concatenates the elements of a to create a single string. The separator string sep is placed between elements in the resulting string.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	s := []string{"foo", "bar", "baz"}
	fmt.Println(strings.Join(s, ", "))
}

foo, bar, baz

Run Format

func LastIndex

func LastIndex(s, sep string) int

LastIndex returns the index of the last instance of sep in s, or -1 if sep is not present in s.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.Index("go gopher", "go"))
	fmt.Println(strings.LastIndex("go gopher", "go"))
	fmt.Println(strings.LastIndex("go gopher", "rodent"))
}

0
3
-1

Run Format

func LastIndexAny

func LastIndexAny(s, chars string) int

LastIndexAny returns the index of the last instance of any Unicode code point from chars in s, or -1 if no Unicode code point from chars is present in s.

func LastIndexByte

func LastIndexByte(s string, c byte) int

LastIndexByte returns the index of the last instance of c in s, or -1 if c is not present in s.

func LastIndexFunc

func LastIndexFunc(s string, f func(rune) bool) int

LastIndexFunc returns the index into s of the last Unicode code point satisfying f(c), or -1 if none do.

func Map

func Map(mapping func(rune) rune, s string) string

Map returns a copy of the string s with all its characters modified according to the mapping function. If mapping returns a negative value, the character is dropped from the string with no replacement.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	rot13 := func(r rune) rune {
		switch {
		case r >= 'A' && r <= 'Z':
			return 'A' + (r-'A'+13)%26
		case r >= 'a' && r <= 'z':
			return 'a' + (r-'a'+13)%26
		}
		return r
	}
	fmt.Println(strings.Map(rot13, "'Twas brillig and the slithy gopher..."))
}

'Gjnf oevyyvt naq gur fyvgul tbcure...

Run Format

func Repeat

func Repeat(s string, count int) string

Repeat returns a new string consisting of count copies of the string s.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println("ba" + strings.Repeat("na", 2))
}

banana

Run Format

func Replace

func Replace(s, old, new string, n int) string

Replace returns a copy of the string s with the first n non-overlapping instances of old replaced by new. If old is empty, it matches at the beginning of the string and after each UTF-8 sequence, yielding up to k+1 replacements for a k-rune string. If n < 0, there is no limit on the number of replacements.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.Replace("oink oink oink", "k", "ky", 2))
	fmt.Println(strings.Replace("oink oink oink", "oink", "moo", -1))
}

oinky oinky oink
moo moo moo

Run Format

func Split

func Split(s, sep string) []string

Split slices s into all substrings separated by sep and returns a slice of the substrings between those separators. If sep is empty, Split splits after each UTF-8 sequence. It is equivalent to SplitN with a count of -1.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Printf("%q\n", strings.Split("a,b,c", ","))
	fmt.Printf("%q\n", strings.Split("a man a plan a canal panama", "a "))
	fmt.Printf("%q\n", strings.Split(" xyz ", ""))
	fmt.Printf("%q\n", strings.Split("", "Bernardo O'Higgins"))
}

["a" "b" "c"]
["" "man " "plan " "canal panama"]
[" " "x" "y" "z" " "]
[""]

Run Format

func SplitAfter

func SplitAfter(s, sep string) []string

SplitAfter slices s into all substrings after each instance of sep and returns a slice of those substrings. If sep is empty, SplitAfter splits after each UTF-8 sequence. It is equivalent to SplitAfterN with a count of -1.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Printf("%q\n", strings.SplitAfter("a,b,c", ","))
}

["a," "b," "c"]

Run Format

func SplitAfterN

func SplitAfterN(s, sep string, n int) []string

SplitAfterN slices s into substrings after each instance of sep and returns a slice of those substrings. If sep is empty, SplitAfterN splits after each UTF-8 sequence. The count determines the number of substrings to return:

n > 0: at most n substrings; the last substring will be the unsplit remainder.
n == 0: the result is nil (zero substrings)
n < 0: all substrings

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Printf("%q\n", strings.SplitAfterN("a,b,c", ",", 2))
}

["a," "b,c"]

Run Format

func SplitN

func SplitN(s, sep string, n int) []string

SplitN slices s into substrings separated by sep and returns a slice of the substrings between those separators. If sep is empty, SplitN splits after each UTF-8 sequence. The count determines the number of substrings to return:

n > 0: at most n substrings; the last substring will be the unsplit remainder.
n == 0: the result is nil (zero substrings)
n < 0: all substrings

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Printf("%q\n", strings.SplitN("a,b,c", ",", 2))
	z := strings.SplitN("a,b,c", ",", 0)
	fmt.Printf("%q (nil = %v)\n", z, z == nil)
}

["a" "b,c"]
[] (nil = true)

Run Format

func Title

func Title(s string) string

Title returns a copy of the string s with all Unicode letters that begin words mapped to their title case.

BUG(rsc): The rule Title uses for word boundaries does not handle Unicode punctuation properly.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.Title("her royal highness"))
}

Her Royal Highness

Run Format

func ToLower

func ToLower(s string) string

ToLower returns a copy of the string s with all Unicode letters mapped to their lower case.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.ToLower("Gopher"))
}

gopher

Run Format

func ToLowerSpecial

func ToLowerSpecial(_case unicode.SpecialCase, s string) string

ToLowerSpecial returns a copy of the string s with all Unicode letters mapped to their lower case, giving priority to the special casing rules.

func ToTitle

func ToTitle(s string) string

ToTitle returns a copy of the string s with all Unicode letters mapped to their title case.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.ToTitle("loud noises"))
	fmt.Println(strings.ToTitle("хлеб"))
}

LOUD NOISES
ХЛЕБ

Run Format

func ToTitleSpecial

func ToTitleSpecial(_case unicode.SpecialCase, s string) string

ToTitleSpecial returns a copy of the string s with all Unicode letters mapped to their title case, giving priority to the special casing rules.

func ToUpper

func ToUpper(s string) string

ToUpper returns a copy of the string s with all Unicode letters mapped to their upper case.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.ToUpper("Gopher"))
}

GOPHER

Run Format

func ToUpperSpecial

func ToUpperSpecial(_case unicode.SpecialCase, s string) string

ToUpperSpecial returns a copy of the string s with all Unicode letters mapped to their upper case, giving priority to the special casing rules.

func Trim

func Trim(s string, cutset string) string

Trim returns a slice of the string s with all leading and trailing Unicode code points contained in cutset removed.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Printf("[%q]", strings.Trim(" !!! Achtung! Achtung! !!! ", "! "))
}

["Achtung! Achtung"]

Run Format

func TrimFunc

func TrimFunc(s string, f func(rune) bool) string

TrimFunc returns a slice of the string s with all leading and trailing Unicode code points c satisfying f(c) removed.

func TrimLeft

func TrimLeft(s string, cutset string) string

TrimLeft returns a slice of the string s with all leading Unicode code points contained in cutset removed.

func TrimLeftFunc

func TrimLeftFunc(s string, f func(rune) bool) string

TrimLeftFunc returns a slice of the string s with all leading Unicode code points c satisfying f(c) removed.

func TrimPrefix

func TrimPrefix(s, prefix string) string

TrimPrefix returns s without the provided leading prefix string. If s doesn't start with prefix, s is returned unchanged.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	var s = "Goodbye,, world!"
	s = strings.TrimPrefix(s, "Goodbye,")
	s = strings.TrimPrefix(s, "Howdy,")
	fmt.Print("Hello" + s)
}

Hello, world!

Run Format

func TrimRight

func TrimRight(s string, cutset string) string

TrimRight returns a slice of the string s, with all trailing Unicode code points contained in cutset removed.

func TrimRightFunc

func TrimRightFunc(s string, f func(rune) bool) string

TrimRightFunc returns a slice of the string s with all trailing Unicode code points c satisfying f(c) removed.

func TrimSpace

func TrimSpace(s string) string

TrimSpace returns a slice of the string s, with all leading and trailing white space removed, as defined by Unicode.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.TrimSpace(" \t\n a lone gopher \n\t\r\n"))
}

a lone gopher

Run Format

func TrimSuffix

func TrimSuffix(s, suffix string) string

TrimSuffix returns s without the provided trailing suffix string. If s doesn't end with suffix, s is returned unchanged.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	var s = "Hello, goodbye, etc!"
	s = strings.TrimSuffix(s, "goodbye, etc!")
	s = strings.TrimSuffix(s, "planet")
	fmt.Print(s, "world!")
}

Hello, world!

Run Format

type Reader

type Reader struct {
        // contains filtered or unexported fields
}

A Reader implements the io.Reader, io.ReaderAt, io.Seeker, io.WriterTo, io.ByteScanner, and io.RuneScanner interfaces by reading from a string.

func NewReader

func NewReader(s string) *Reader

NewReader returns a new Reader reading from s. It is similar to bytes.NewBufferString but more efficient and read-only.

func (*Reader) Len

func (r *Reader) Len() int

Len returns the number of bytes of the unread portion of the string.

func (*Reader) Read

func (r *Reader) Read(b []byte) (n int, err error)

func (*Reader) ReadAt

func (r *Reader) ReadAt(b []byte, off int64) (n int, err error)

func (*Reader) ReadByte

func (r *Reader) ReadByte() (b byte, err error)

func (*Reader) ReadRune

func (r *Reader) ReadRune() (ch rune, size int, err error)

func (*Reader) Seek

func (r *Reader) Seek(offset int64, whence int) (int64, error)

Seek implements the io.Seeker interface.

func (*Reader) Size

func (r *Reader) Size() int64

Size returns the original length of the underlying string. Size is the number of bytes available for reading via ReadAt. The returned value is always the same and is not affected by calls to any other method.

func (*Reader) UnreadByte

func (r *Reader) UnreadByte() error

func (*Reader) UnreadRune

func (r *Reader) UnreadRune() error

func (*Reader) WriteTo

func (r *Reader) WriteTo(w io.Writer) (n int64, err error)

WriteTo implements the io.WriterTo interface.

type Replacer

type Replacer struct {
        // contains filtered or unexported fields
}

Replacer replaces a list of strings with replacements. It is safe for concurrent use by multiple goroutines.

func NewReplacer

func NewReplacer(oldnew ...string) *Replacer

NewReplacer returns a new Replacer from a list of old, new string pairs. Replacements are performed in order, without overlapping matches.

▹ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	r := strings.NewReplacer("<", "&lt;", ">", "&gt;")
	fmt.Println(r.Replace("This is <b>HTML</b>!"))
}

This is &lt;b&gt;HTML&lt;/b&gt;!

Run Format

func (*Replacer) Replace

func (r *Replacer) Replace(s string) string

Replace returns a copy of s with all replacements performed.

func (*Replacer) WriteString

func (r *Replacer) WriteString(w io.Writer, s string) (n int, err error)

WriteString writes s to w with all replacements performed.

Bugs

☞
The rule Title uses for word boundaries does not handle Unicode punctuation properly.