version: 1.10

package strings

import "strings"

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

Examples

Package files

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

func Compare 

  1. 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: fmt.Println(strings.Compare(“a”, “b”)) fmt.Println(strings.Compare(“a”, “a”)) fmt.Println(strings.Compare(“b”, “a”)) // Output: // -1 // 0 // 1

func Contains 

  1. func Contains(s, substr string) bool
Contains reports whether substr is within s. Example: fmt.Println(strings.Contains(“seafood”, “foo”)) fmt.Println(strings.Contains(“seafood”, “bar”)) fmt.Println(strings.Contains(“seafood”, “”)) fmt.Println(strings.Contains(“”, “”)) // Output: // true // false // true // true

func ContainsAny 

  1. func ContainsAny(s, chars string) bool
ContainsAny reports whether any Unicode code points in chars are within s. Example: fmt.Println(strings.ContainsAny(“team”, “i”)) fmt.Println(strings.ContainsAny(“failure”, “u & i”)) fmt.Println(strings.ContainsAny(“foo”, “”)) fmt.Println(strings.ContainsAny(“”, “”)) // Output: // false // true // false // false

func ContainsRune 

  1. func ContainsRune(s string, r rune) bool
ContainsRune reports whether the Unicode code point r is within s. Example: // Finds whether a string contains a particular Unicode code point. // The code point for the lowercase letter “a”, for example, is 97. fmt.Println(strings.ContainsRune(“aardvark”, 97)) fmt.Println(strings.ContainsRune(“timeout”, 97)) // Output: // true // false

func Count 

  1. 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: fmt.Println(strings.Count(“cheese”, “e”)) fmt.Println(strings.Count(“five”, “”)) // before & after each rune // Output: // 3 // 5

func EqualFold 

  1. func EqualFold(s, t string) bool
EqualFold reports whether s and t, interpreted as UTF-8 strings, are equal under Unicode case-folding. Example: fmt.Println(strings.EqualFold(“Go”, “go”)) // Output: true

func Fields 

  1. 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: fmt.Printf(“Fields are: %q”, strings.Fields(“ foo bar baz “)) // Output: Fields are: [“foo” “bar” “baz”]

func FieldsFunc 

  1. 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: f := func(c rune) bool { return !unicode.IsLetter(c) && !unicode.IsNumber(c) } fmt.Printf(“Fields are: %q”, strings.FieldsFunc(“ foo1;bar2,baz3…”, f)) // Output: Fields are: [“foo1” “bar2” “baz3”]

func HasPrefix 

  1. func HasPrefix(s, prefix string) bool
HasPrefix tests whether the string s begins with prefix. Example: fmt.Println(strings.HasPrefix(“Gopher”, “Go”)) fmt.Println(strings.HasPrefix(“Gopher”, “C”)) fmt.Println(strings.HasPrefix(“Gopher”, “”)) // Output: // true // false // true

func HasSuffix 

  1. func HasSuffix(s, suffix string) bool
HasSuffix tests whether the string s ends with suffix. Example: fmt.Println(strings.HasSuffix(“Amigo”, “go”)) fmt.Println(strings.HasSuffix(“Amigo”, “O”)) fmt.Println(strings.HasSuffix(“Amigo”, “Ami”)) fmt.Println(strings.HasSuffix(“Amigo”, “”)) // Output: // true // false // false // true

func Index 

  1. 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: fmt.Println(strings.Index(“chicken”, “ken”)) fmt.Println(strings.Index(“chicken”, “dmr”)) // Output: // 4 // -1

func IndexAny 

  1. 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: fmt.Println(strings.IndexAny(“chicken”, “aeiouy”)) fmt.Println(strings.IndexAny(“crwth”, “aeiouy”)) // Output: // 2 // -1

func IndexByte 

  1. 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: fmt.Println(strings.IndexByte(“golang”, ‘g’)) fmt.Println(strings.IndexByte(“gophers”, ‘h’)) fmt.Println(strings.IndexByte(“golang”, ‘x’)) // Output: // 0 // 3 // -1

func IndexFunc 

  1. 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: 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)) // Output: // 7 // -1

func IndexRune 

  1. 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: fmt.Println(strings.IndexRune(“chicken”, ‘k’)) fmt.Println(strings.IndexRune(“chicken”, ‘d’)) // Output: // 4 // -1

func Join 

  1. 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: s := []string{“foo”, “bar”, “baz”} fmt.Println(strings.Join(s, “, “)) // Output: foo, bar, baz

func LastIndex 

  1. 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: fmt.Println(strings.Index(“go gopher”, “go”)) fmt.Println(strings.LastIndex(“go gopher”, “go”)) fmt.Println(strings.LastIndex(“go gopher”, “rodent”)) // Output: // 0 // 3 // -1

func LastIndexAny 

  1. 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: fmt.Println(strings.LastIndexAny(“go gopher”, “go”)) fmt.Println(strings.LastIndexAny(“go gopher”, “rodent”)) fmt.Println(strings.LastIndexAny(“go gopher”, “fail”)) // Output: // 4 // 8 // -1

func LastIndexByte 

  1. 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: fmt.Println(strings.LastIndexByte(“Hello, world”, ‘l’)) fmt.Println(strings.LastIndexByte(“Hello, world”, ‘o’)) fmt.Println(strings.LastIndexByte(“Hello, world”, ‘x’)) // Output: // 10 // 8 // -1

func LastIndexFunc 

  1. 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: fmt.Println(strings.LastIndexFunc(“go 123”, unicode.IsNumber)) fmt.Println(strings.LastIndexFunc(“123 go”, unicode.IsNumber)) fmt.Println(strings.LastIndexFunc(“go”, unicode.IsNumber)) // Output: // 5 // 2 // -1

func Map 

  1. 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: 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…”)) // Output: ‘Gjnf oevyyvt naq gur fyvgul tbcure…

func Repeat 

  1. 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: fmt.Println(“ba” + strings.Repeat(“na”, 2)) // Output: banana

func Replace 

  1. 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: fmt.Println(strings.Replace(“oink oink oink”, “k”, “ky”, 2)) fmt.Println(strings.Replace(“oink oink oink”, “oink”, “moo”, -1)) // Output: // oinky oinky oink // moo moo moo

func Split 

  1. 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: 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”)) // Output: // [“a” “b” “c”] // [“” “man “ “plan “ “canal panama”] // [“ “ “x” “y” “z” “ “] // [“”]

func SplitAfter 

  1. 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: fmt.Printf(“%q\n”, strings.SplitAfter(“a,b,c”, “,”)) // Output: [“a,” “b,” “c”]

func SplitAfterN 

  1. 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: fmt.Printf(“%q\n”, strings.SplitAfterN(“a,b,c”, “,”, 2)) // Output: [“a,” “b,c”]

func SplitN 

  1. 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: 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) // Output: // [“a” “b,c”] // [] (nil = true)

func Title 

  1. 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: fmt.Println(strings.Title(“her royal highness”)) // Output: Her Royal Highness

func ToLower 

  1. func ToLower(s string) string
ToLower returns a copy of the string s with all Unicode letters mapped to their lower case. Example: fmt.Println(strings.ToLower(“Gopher”)) // Output: gopher

func ToLowerSpecial 

  1. 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: fmt.Println(strings.ToLowerSpecial(unicode.TurkishCase, “Önnek İş”)) // Output: önnek iş

func ToTitle 

  1. func ToTitle(s string) string
ToTitle returns a copy of the string s with all Unicode letters mapped to their title case. Example: fmt.Println(strings.ToTitle(“loud noises”)) fmt.Println(strings.ToTitle(“хлеб”)) // Output: // LOUD NOISES // ХЛЕБ

func ToTitleSpecial 

  1. 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: fmt.Println(strings.ToTitleSpecial(unicode.TurkishCase, “dünyanın ilk borsa yapısı Aizonai kabul edilir”)) // Output: // DÜNYANIN İLK BORSA YAPISI AİZONAİ KABUL EDİLİR

func ToUpper 

  1. func ToUpper(s string) string
ToUpper returns a copy of the string s with all Unicode letters mapped to their upper case. Example: fmt.Println(strings.ToUpper(“Gopher”)) // Output: GOPHER

func ToUpperSpecial 

  1. 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: fmt.Println(strings.ToUpperSpecial(unicode.TurkishCase, “örnek iş”)) // Output: ÖRNEK İŞ

func Trim 

  1. 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: fmt.Print(strings.Trim(“¡¡¡Hello, Gophers!!!”, “!¡”)) // Output: Hello, Gophers

func TrimFunc 

  1. 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: fmt.Print(strings.TrimFunc(“¡¡¡Hello, Gophers!!!”, func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsNumber(r) })) // Output: Hello, Gophers

func TrimLeft 

  1. 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: fmt.Print(strings.TrimLeft(“¡¡¡Hello, Gophers!!!”, “!¡”)) // Output: Hello, Gophers!!!

func TrimLeftFunc 

  1. 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: fmt.Print(strings.TrimLeftFunc(“¡¡¡Hello, Gophers!!!”, func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsNumber(r) })) // Output: Hello, Gophers!!!

func TrimPrefix 

  1. 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: var s = “¡¡¡Hello, Gophers!!!” s = strings.TrimPrefix(s, “¡¡¡Hello, “) s = strings.TrimPrefix(s, “¡¡¡Howdy, “) fmt.Print(s) // Output: Gophers!!!

func TrimRight 

  1. 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: fmt.Print(strings.TrimRight(“¡¡¡Hello, Gophers!!!”, “!¡”)) // Output: ¡¡¡Hello, Gophers

func TrimRightFunc 

  1. 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: fmt.Print(strings.TrimRightFunc(“¡¡¡Hello, Gophers!!!”, func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsNumber(r) })) // Output: ¡¡¡Hello, Gophers

func TrimSpace 

  1. 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: fmt.Println(strings.TrimSpace(“ \t\n Hello, Gophers \n\t\r\n”)) // Output: Hello, Gophers

func TrimSuffix 

  1. 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: var s = “¡¡¡Hello, Gophers!!!” s = strings.TrimSuffix(s, “, Gophers!!!”) s = strings.TrimSuffix(s, “, Marmots!!!”) fmt.Print(s) // Output: ¡¡¡Hello

type Builder 

  1. type Builder struct {
  2.     // contains filtered or unexported fields
  3. }
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. Example: var b strings.Builder for i := 3; i >= 1; i— { fmt.Fprintf(&b, “%d…”, i) } b.WriteString(“ignition”) fmt.Println(b.String()) // Output: 3…2…1…ignition

func (Builder) Grow 

  1. 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 

  1. func (b Builder) Len() int
Len returns the number of accumulated bytes; b.Len() == len(b.String()).

func (Builder) Reset 

  1. func (b Builder) Reset()
Reset resets the Builder to be empty.

func (Builder) String 

  1. func (b Builder) String() string
String returns the accumulated string.

func (Builder) Write 

  1. 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 

  1. 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 

  1. 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 

  1. 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 

  1. type Reader struct {
  2.     // contains filtered or unexported fields
  3. }
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 

  1. 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 

  1. func (r Reader) Len() int
Len returns the number of bytes of the unread portion of the string.

func (Reader) Read 

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

func (Reader) ReadAt 

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

func (Reader) ReadByte 

  1. func (r Reader) ReadByte() (byte, error)

func (Reader) ReadRune 

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

func (Reader) Reset 

  1. func (r Reader) Reset(s string)
Reset resets the Reader to be reading from s.

func (Reader) Seek 

  1. func (r Reader) Seek(offset int64, whence int) (int64, error)
Seek implements the io.Seeker interface.

func (Reader) Size 

  1. 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 

  1. func (r Reader) UnreadByte() error

func (Reader) UnreadRune 

  1. func (r Reader) UnreadRune() error

func (Reader) WriteTo 

  1. func (r Reader) WriteTo(w io.Writer) (n int64, err error)
WriteTo implements the io.WriterTo interface.

type Replacer 

  1. type Replacer struct {
  2.     // contains filtered or unexported fields
  3. }
Replacer replaces a list of strings with replacements. It is safe for concurrent use by multiple goroutines.

func NewReplacer 

  1. 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: r := strings.NewReplacer(“<”, “<”, “>”, “>”) fmt.Println(r.Replace(“This is HTML!”)) // Output: This is <b>HTML</b>!

func (Replacer) Replace 

  1. func (r Replacer) Replace(s string) string
Replace returns a copy of s with all replacements performed.

func (Replacer) WriteString 

  1. 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.