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Package strings

import "strings"
Overview
Index
Examples

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 ▾

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, substr 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, substr 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, substr 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(c unicode.SpecialCase, s string) string
func ToTitle(s string) string
func ToTitleSpecial(c unicode.SpecialCase, s string) string
func ToUpper(s string) string
func ToUpperSpecial(c 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
type Builder
    func (b *Builder) Grow(n int)
    func (b *Builder) Len() int
    func (b *Builder) Reset()
    func (b *Builder) String() string
    func (b *Builder) Write(p []byte) (int, error)
    func (b *Builder) WriteByte(c byte) error
    func (b *Builder) WriteRune(r rune) (int, error)
    func (b *Builder) WriteString(s string) (int, error)
type Reader
    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() (byte, error)
    func (r *Reader) ReadRune() (ch rune, size int, err error)
    func (r *Reader) Reset(s string)
    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)
type Replacer
    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)
Bugs

Package files

builder.go 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.

Example

-1
0
1

func Contains

func Contains(s, substr string) bool

Contains reports whether substr is within s.

Example

true
false
true
true

func ContainsAny

func ContainsAny(s, chars string) bool

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

Example

false
true
false
false

func ContainsRune

func ContainsRune(s string, r rune) bool

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

Example

true
false

func Count

func Count(s, substr string) int

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

Example

3
5

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

true

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 a slice of substrings of s or an empty slice if s contains only white space.

Example

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

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

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

func HasPrefix

func HasPrefix(s, prefix string) bool

HasPrefix tests whether the string s begins with prefix.

Example

true
false
true

func HasSuffix

func HasSuffix(s, suffix string) bool

HasSuffix tests whether the string s ends with suffix.

Example

true
false
false
true

func Index

func Index(s, substr string) int

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

Example

4
-1

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

2
-1

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.

Example

0
3
-1

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

7
-1

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. If r is utf8.RuneError, it returns the first instance of any invalid UTF-8 byte sequence.

Example

4
-1

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

foo, bar, baz

func LastIndex

func LastIndex(s, substr string) int

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

Example

0
3
-1

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.

Example

4
8
-1

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.

Example

10
8
-1

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.

Example

5
2
-1

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

'Gjnf oevyyvt naq gur fyvgul tbcure...

func Repeat

func Repeat(s string, count int) string

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

It panics if count is negative or if the result of (len(s) * count) overflows.

Example

banana

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

oinky oinky oink
moo moo moo

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 s does not contain sep and sep is not empty, Split returns a slice of length 1 whose only element is s.

If sep is empty, Split splits after each UTF-8 sequence. If both s and sep are empty, Split returns an empty slice.

It is equivalent to SplitN with a count of -1.

Example

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

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 s does not contain sep and sep is not empty, SplitAfter returns a slice of length 1 whose only element is s.

If sep is empty, SplitAfter splits after each UTF-8 sequence. If both s and sep are empty, SplitAfter returns an empty slice.

It is equivalent to SplitAfterN with a count of -1.

Example

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

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.

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

Edge cases for s and sep (for example, empty strings) are handled as described in the documentation for SplitAfter.

Example

["a," "b,c"]

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.

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

Edge cases for s and sep (for example, empty strings) are handled as described in the documentation for Split.

Example

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

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

Her Royal Highness

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

gopher

func ToLowerSpecial

func ToLowerSpecial(c 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.

Example

önnek iş

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

LOUD NOISES
ХЛЕБ

func ToTitleSpecial

func ToTitleSpecial(c 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.

Example

DÜNYANIN İLK BORSA YAPISI AİZONAİ KABUL EDİLİR

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

GOPHER

func ToUpperSpecial

func ToUpperSpecial(c 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.

Example

ÖRNEK İŞ

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

Hello, Gophers

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.

Example

Hello, Gophers

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.

Example

Hello, Gophers!!!

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.

Example

Hello, Gophers!!!

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

Gophers!!!

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.

Example

¡¡¡Hello, Gophers

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.

Example

¡¡¡Hello, Gophers

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

Hello, Gophers

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

¡¡¡Hello

type Builder

A Builder is used to efficiently build a string using Write methods. It minimizes memory copying. The zero value is ready to use. Do not copy a non-zero Builder.

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

Example

3...2...1...ignition

func (*Builder) Grow

func (b *Builder) Grow(n int)

Grow grows b's capacity, if necessary, to guarantee space for another n bytes. After Grow(n), at least n bytes can be written to b without another allocation. If n is negative, Grow panics.

func (*Builder) Len

func (b *Builder) Len() int

Len returns the number of accumulated bytes; b.Len() == len(b.String()).

func (*Builder) Reset

func (b *Builder) Reset()

Reset resets the Builder to be empty.

func (*Builder) String

func (b *Builder) String() string

String returns the accumulated string.

func (*Builder) Write

func (b *Builder) Write(p []byte) (int, error)

Write appends the contents of p to b's buffer. Write always returns len(p), nil.

func (*Builder) WriteByte

func (b *Builder) WriteByte(c byte) error

WriteByte appends the byte c to b's buffer. The returned error is always nil.

func (*Builder) WriteRune

func (b *Builder) WriteRune(r rune) (int, error)

WriteRune appends the UTF-8 encoding of Unicode code point r to b's buffer. It returns the length of r and a nil error.

func (*Builder) WriteString

func (b *Builder) WriteString(s string) (int, error)

WriteString appends the contents of s to b's buffer. It returns the length of s and a nil error.

type Reader

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

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

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() (byte, error)

func (*Reader) ReadRune

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

func (*Reader) Reset

func (r *Reader) Reset(s string)

Reset resets the Reader to be reading from s.

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

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

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

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

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

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