strings
Package 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
compare.go reader.go replace.go search.go strings.go strings_amd64.go strings_decl.go
func CompareSource
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 ContainsSource
func Contains(s, substr string) bool
Contains reports whether substr is within s.
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("", "")) }
func ContainsAnySource
func ContainsAny(s, chars string) bool
ContainsAny reports whether any Unicode code points in chars are within s.
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("", "")) }
func ContainsRuneSource
func ContainsRune(s string, r rune) bool
ContainsRune reports whether the Unicode code point r is within s.
func CountSource
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
package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.Count("cheese", "e")) fmt.Println(strings.Count("five", "")) // before & after each rune }
func EqualFoldSource
func EqualFold(s, t string) bool
EqualFold reports whether s and t, interpreted as UTF-8 strings, are equal under Unicode case-folding.
Example
package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.EqualFold("Go", "go")) }
func FieldsSource
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
package main import ( "fmt" "strings" ) func main() { fmt.Printf("Fields are: %q", strings.Fields(" foo bar baz ")) }
func FieldsFuncSource
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
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)) }
func HasPrefixSource
func HasPrefix(s, prefix string) bool
HasPrefix tests whether the string s begins with prefix.
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", "")) }
func HasSuffixSource
func HasSuffix(s, suffix string) bool
HasSuffix tests whether the string s ends with suffix.
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", "")) }
func IndexSource
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
package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.Index("chicken", "ken")) fmt.Println(strings.Index("chicken", "dmr")) }
func IndexAnySource
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
package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.IndexAny("chicken", "aeiouy")) fmt.Println(strings.IndexAny("crwth", "aeiouy")) }
func IndexByteSource
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 IndexFuncSource
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
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)) }
func IndexRuneSource
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
package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.IndexRune("chicken", 'k')) fmt.Println(strings.IndexRune("chicken", 'd')) }
func JoinSource
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
package main import ( "fmt" "strings" ) func main() { s := []string{"foo", "bar", "baz"} fmt.Println(strings.Join(s, ", ")) }
func LastIndexSource
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
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")) }
func LastIndexAnySource
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 LastIndexByteSource
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 LastIndexFuncSource
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 MapSource
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
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...")) }
func RepeatSource
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
package main import ( "fmt" "strings" ) func main() { fmt.Println("ba" + strings.Repeat("na", 2)) }
func ReplaceSource
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
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)) }
func SplitSource
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
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")) }
func SplitAfterSource
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
package main import ( "fmt" "strings" ) func main() { fmt.Printf("%q\n", strings.SplitAfter("a,b,c", ",")) }
func SplitAfterNSource
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
package main import ( "fmt" "strings" ) func main() { fmt.Printf("%q\n", strings.SplitAfterN("a,b,c", ",", 2)) }
func SplitNSource
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
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) }
func TitleSource
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
package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.Title("her royal highness")) }
func ToLowerSource
func ToLower(s string) string
ToLower returns a copy of the string s with all Unicode letters mapped to their lower case.
Example
package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.ToLower("Gopher")) }
func ToLowerSpecialSource
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.
func ToTitleSource
func ToTitle(s string) string
ToTitle returns a copy of the string s with all Unicode letters mapped to their title case.
Example
package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.ToTitle("loud noises")) fmt.Println(strings.ToTitle("хлеб")) }
func ToTitleSpecialSource
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.
func ToUpperSource
func ToUpper(s string) string
ToUpper returns a copy of the string s with all Unicode letters mapped to their upper case.
Example
package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.ToUpper("Gopher")) }
func ToUpperSpecialSource
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.
func TrimSource
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
package main import ( "fmt" "strings" ) func main() { fmt.Printf("[%q]", strings.Trim(" !!! Achtung! Achtung! !!! ", "! ")) }
func TrimFuncSource
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 TrimLeftSource
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 TrimLeftFuncSource
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 TrimPrefixSource
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
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) }
func TrimRightSource
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 TrimRightFuncSource
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 TrimSpaceSource
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
package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.TrimSpace(" \t\n a lone gopher \n\t\r\n")) }
func TrimSuffixSource
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
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!") }
type ReaderSource
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 NewReaderSource
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) LenSource
func (r *Reader) Len() int
Len returns the number of bytes of the unread portion of the string.
func (*Reader) ReadSource
func (r *Reader) Read(b []byte) (n int, err error)
func (*Reader) ReadAtSource
func (r *Reader) ReadAt(b []byte, off int64) (n int, err error)
func (*Reader) ReadByteSource
func (r *Reader) ReadByte() (byte, error)
func (*Reader) ReadRuneSource
func (r *Reader) ReadRune() (ch rune, size int, err error)
func (*Reader) ResetSource
func (r *Reader) Reset(s string)
Reset resets the Reader to be reading from s.
func (*Reader) SeekSource
func (r *Reader) Seek(offset int64, whence int) (int64, error)
Seek implements the io.Seeker interface.
func (*Reader) SizeSource
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) UnreadByteSource
func (r *Reader) UnreadByte() error
func (*Reader) UnreadRuneSource
func (r *Reader) UnreadRune() error
func (*Reader) WriteToSource
func (r *Reader) WriteTo(w io.Writer) (n int64, err error)
WriteTo implements the io.WriterTo interface.
type ReplacerSource
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 NewReplacerSource
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
package main import ( "fmt" "strings" ) func main() { r := strings.NewReplacer("<", "<", ">", ">") fmt.Println(r.Replace("This is <b>HTML</b>!")) }
func (*Replacer) ReplaceSource
func (r *Replacer) Replace(s string) string
Replace returns a copy of s with all replacements performed.
func (*Replacer) WriteStringSource
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.
© Google, Inc.
Licensed under the Creative Commons Attribution License 3.0.
https://golang.org/pkg/strings/