package strings

Import Path
	strings (on golang.org and go.dev)

Dependency Relation
	imports 7 packages, and imported by 75 packages

Involved Source Files builder.go compare.go reader.go replace.go search.go 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.
Code Examples package main import ( "fmt" "strings" ) func main() { var b strings.Builder for i := 3; i >= 1; i-- { fmt.Fprintf(&b, "%d...", i) } b.WriteString("ignition") fmt.Println(b.String()) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.Compare("a", "b")) fmt.Println(strings.Compare("a", "a")) fmt.Println(strings.Compare("b", "a")) } 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("", "")) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.ContainsAny("team", "i")) fmt.Println(strings.ContainsAny("fail", "ui")) fmt.Println(strings.ContainsAny("ure", "ui")) fmt.Println(strings.ContainsAny("failure", "ui")) fmt.Println(strings.ContainsAny("foo", "")) fmt.Println(strings.ContainsAny("", "")) } package main import ( "fmt" "strings" ) func main() { // 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)) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.Count("cheese", "e")) fmt.Println(strings.Count("five", "")) // before & after each rune } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.EqualFold("Go", "go")) } package main import ( "fmt" "strings" ) func main() { fmt.Printf("Fields are: %q", strings.Fields(" foo bar baz ")) } 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)) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.HasPrefix("Gopher", "Go")) fmt.Println(strings.HasPrefix("Gopher", "C")) fmt.Println(strings.HasPrefix("Gopher", "")) } 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", "")) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.Index("chicken", "ken")) fmt.Println(strings.Index("chicken", "dmr")) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.IndexAny("chicken", "aeiouy")) fmt.Println(strings.IndexAny("crwth", "aeiouy")) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.IndexByte("golang", 'g')) fmt.Println(strings.IndexByte("gophers", 'h')) fmt.Println(strings.IndexByte("golang", 'x')) } 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)) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.IndexRune("chicken", 'k')) fmt.Println(strings.IndexRune("chicken", 'd')) } package main import ( "fmt" "strings" ) func main() { s := []string{"foo", "bar", "baz"} fmt.Println(strings.Join(s, ", ")) } 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")) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.LastIndexAny("go gopher", "go")) fmt.Println(strings.LastIndexAny("go gopher", "rodent")) fmt.Println(strings.LastIndexAny("go gopher", "fail")) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.LastIndexByte("Hello, world", 'l')) fmt.Println(strings.LastIndexByte("Hello, world", 'o')) fmt.Println(strings.LastIndexByte("Hello, world", 'x')) } package main import ( "fmt" "strings" "unicode" ) func main() { fmt.Println(strings.LastIndexFunc("go 123", unicode.IsNumber)) fmt.Println(strings.LastIndexFunc("123 go", unicode.IsNumber)) fmt.Println(strings.LastIndexFunc("go", unicode.IsNumber)) } 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...")) } package main import ( "fmt" "strings" ) func main() { r := strings.NewReplacer("<", "<", ">", ">") fmt.Println(r.Replace("This is HTML!")) } package main import ( "fmt" "strings" ) func main() { fmt.Println("ba" + strings.Repeat("na", 2)) } 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)) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.ReplaceAll("oink oink oink", "oink", "moo")) } 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")) } package main import ( "fmt" "strings" ) func main() { fmt.Printf("%q\n", strings.SplitAfter("a,b,c", ",")) } package main import ( "fmt" "strings" ) func main() { fmt.Printf("%q\n", strings.SplitAfterN("a,b,c", ",", 2)) } 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) } package main import ( "fmt" "strings" ) func main() { // Compare this example to the ToTitle example. fmt.Println(strings.Title("her royal highness")) fmt.Println(strings.Title("loud noises")) fmt.Println(strings.Title("хлеб")) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.ToLower("Gopher")) } package main import ( "fmt" "strings" "unicode" ) func main() { fmt.Println(strings.ToLowerSpecial(unicode.TurkishCase, "Önnek İş")) } package main import ( "fmt" "strings" ) func main() { // Compare this example to the Title example. fmt.Println(strings.ToTitle("her royal highness")) fmt.Println(strings.ToTitle("loud noises")) fmt.Println(strings.ToTitle("хлеб")) } package main import ( "fmt" "strings" "unicode" ) func main() { fmt.Println(strings.ToTitleSpecial(unicode.TurkishCase, "dünyanın ilk borsa yapısı Aizonai kabul edilir")) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.ToUpper("Gopher")) } package main import ( "fmt" "strings" "unicode" ) func main() { fmt.Println(strings.ToUpperSpecial(unicode.TurkishCase, "örnek iş")) } package main import ( "fmt" "strings" ) func main() { fmt.Print(strings.Trim("¡¡¡Hello, Gophers!!!", "!¡")) } package main import ( "fmt" "strings" "unicode" ) func main() { fmt.Print(strings.TrimFunc("¡¡¡Hello, Gophers!!!", func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsNumber(r) })) } package main import ( "fmt" "strings" ) func main() { fmt.Print(strings.TrimLeft("¡¡¡Hello, Gophers!!!", "!¡")) } package main import ( "fmt" "strings" "unicode" ) func main() { fmt.Print(strings.TrimLeftFunc("¡¡¡Hello, Gophers!!!", func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsNumber(r) })) } package main import ( "fmt" "strings" ) func main() { var s = "¡¡¡Hello, Gophers!!!" s = strings.TrimPrefix(s, "¡¡¡Hello, ") s = strings.TrimPrefix(s, "¡¡¡Howdy, ") fmt.Print(s) } package main import ( "fmt" "strings" ) func main() { fmt.Print(strings.TrimRight("¡¡¡Hello, Gophers!!!", "!¡")) } package main import ( "fmt" "strings" "unicode" ) func main() { fmt.Print(strings.TrimRightFunc("¡¡¡Hello, Gophers!!!", func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsNumber(r) })) } package main import ( "fmt" "strings" ) func main() { fmt.Println(strings.TrimSpace(" \t\n Hello, Gophers \n\t\r\n")) } package main import ( "fmt" "strings" ) func main() { var s = "¡¡¡Hello, Gophers!!!" s = strings.TrimSuffix(s, ", Gophers!!!") s = strings.TrimSuffix(s, ", Marmots!!!") fmt.Print(s) }
Package-Level Type Names (total 3)
/* sort by: | */
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. Cap returns the capacity of the builder's underlying byte slice. It is the total space allocated for the string being built and includes any bytes already written. 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. Len returns the number of accumulated bytes; b.Len() == len(b.String()). Reset resets the Builder to be empty. String returns the accumulated string. Write appends the contents of p to b's buffer. Write always returns len(p), nil. WriteByte appends the byte c to b's buffer. The returned error is always nil. 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. WriteString appends the contents of s to b's buffer. It returns the length of s and a nil error. *T : expvar.Var *T : fmt.Stringer *T : io.ByteWriter *T : io.StringWriter *T : io.Writer
A Reader implements the io.Reader, io.ReaderAt, io.ByteReader, io.ByteScanner, io.RuneReader, io.RuneScanner, io.Seeker, and io.WriterTo interfaces by reading from a string. The zero value for Reader operates like a Reader of an empty string. Len returns the number of bytes of the unread portion of the string. Read implements the io.Reader interface. ReadAt implements the io.ReaderAt interface. ReadByte implements the io.ByteReader interface. ReadRune implements the io.RuneReader interface. Reset resets the Reader to be reading from s. Seek implements the io.Seeker interface. 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. UnreadByte implements the io.ByteScanner interface. UnreadRune implements the io.RuneScanner interface. WriteTo implements the io.WriterTo interface. *T : compress/flate.Reader *T : image/jpeg.Reader *T : io.ByteReader *T : io.ByteScanner *T : io.Reader *T : io.ReaderAt *T : io.ReadSeeker *T : io.RuneReader *T : io.RuneScanner *T : io.Seeker *T : io.WriterTo func NewReader(s string) *Reader
Replacer replaces a list of strings with replacements. It is safe for concurrent use by multiple goroutines. Replace returns a copy of s with all replacements performed. WriteString writes s to w with all replacements performed. func NewReplacer(oldnew ...string) *Replacer
Package-Level Functions (total 47)
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.
Contains reports whether substr is within s.
ContainsAny reports whether any Unicode code points in chars are within s.
ContainsRune reports whether the Unicode code point r is within s.
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.
EqualFold reports whether s and t, interpreted as UTF-8 strings, are equal under Unicode case-folding, which is a more general form of case-insensitivity.
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.
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) and assumes that f always returns the same value for a given c.
HasPrefix tests whether the string s begins with prefix.
HasSuffix tests whether the string s ends with suffix.
Index returns the index of the first instance of substr in s, or -1 if substr is not present in s.
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.
IndexByte returns the index of the first instance of c in s, or -1 if c is not present in s.
IndexFunc returns the index into s of the first Unicode code point satisfying f(c), or -1 if none do.
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.
Join concatenates the elements of its first argument to create a single string. The separator string sep is placed between elements in the resulting string.
LastIndex returns the index of the last instance of substr in s, or -1 if substr is not present in s.
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.
LastIndexByte returns the index of the last instance of c in s, or -1 if c is not present in s.
LastIndexFunc returns the index into s of the last Unicode code point satisfying f(c), or -1 if none do.
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.
NewReader returns a new Reader reading from s. It is similar to bytes.NewBufferString but more efficient and read-only.
NewReplacer returns a new Replacer from a list of old, new string pairs. Replacements are performed in the order they appear in the target string, without overlapping matches. The old string comparisons are done in argument order. NewReplacer panics if given an odd number of arguments.
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.
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.
ReplaceAll returns a copy of the string s with all 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.
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.
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.
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.
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.
Title returns a copy of the string s with all Unicode letters that begin words mapped to their Unicode title case. BUG(rsc): The rule Title uses for word boundaries does not handle Unicode punctuation properly.
ToLower returns s with all Unicode letters mapped to their lower case.
ToLowerSpecial returns a copy of the string s with all Unicode letters mapped to their lower case using the case mapping specified by c.
ToTitle returns a copy of the string s with all Unicode letters mapped to their Unicode title case.
ToTitleSpecial returns a copy of the string s with all Unicode letters mapped to their Unicode title case, giving priority to the special casing rules.
ToUpper returns s with all Unicode letters mapped to their upper case.
ToUpperSpecial returns a copy of the string s with all Unicode letters mapped to their upper case using the case mapping specified by c.
ToValidUTF8 returns a copy of the string s with each run of invalid UTF-8 byte sequences replaced by the replacement string, which may be empty.
Trim returns a slice of the string s with all leading and trailing Unicode code points contained in cutset removed.
TrimFunc returns a slice of the string s with all leading and trailing Unicode code points c satisfying f(c) removed.
TrimLeft returns a slice of the string s with all leading Unicode code points contained in cutset removed. To remove a prefix, use TrimPrefix instead.
TrimLeftFunc returns a slice of the string s with all leading Unicode code points c satisfying f(c) removed.
TrimPrefix returns s without the provided leading prefix string. If s doesn't start with prefix, s is returned unchanged.
TrimRight returns a slice of the string s, with all trailing Unicode code points contained in cutset removed. To remove a suffix, use TrimSuffix instead.
TrimRightFunc returns a slice of the string s with all trailing Unicode code points c satisfying f(c) removed.
TrimSpace returns a slice of the string s, with all leading and trailing white space removed, as defined by Unicode.
TrimSuffix returns s without the provided trailing suffix string. If s doesn't end with suffix, s is returned unchanged.