Documentation
¶
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 Clone(s string) string
- func Compare(a, b string) int
- func Contains(s, substr string) bool
- func ContainsAny(s, chars string) bool
- func ContainsFunc(s string, f func(rune) bool) bool
- func ContainsRune(s string, r rune) bool
- func Count(s, substr string) int
- func Cut(s, sep string) (before, after string, found bool)
- func CutLast(s, sep string) (before, after string, found bool)
- func CutPrefix(s, prefix string) (after string, found bool)
- func CutSuffix(s, suffix string) (before string, found bool)
- func EqualFold(s, t string) bool
- func Fields(s string) []string
- func FieldsFunc(s string, f func(rune) bool) []string
- func FieldsFuncSeq(s string, f func(rune) bool) iter.Seq[string]
- func FieldsSeq(s string) iter.Seq[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(elems []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 Lines(s string) iter.Seq[string]
- 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 ReplaceAll(s, old, new string) string
- func Split(s, sep string) []string
- func SplitAfter(s, sep string) []string
- func SplitAfterN(s, sep string, n int) []string
- func SplitAfterSeq(s, sep string) iter.Seq[string]
- func SplitN(s, sep string, n int) []string
- func SplitSeq(s, sep string) iter.Seq[string]
- func Title(s string) stringdeprecated
- 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 ToValidUTF8(s, replacement string) string
- func Trim(s, cutset string) string
- func TrimFunc(s string, f func(rune) bool) string
- func TrimLeft(s, cutset string) string
- func TrimLeftFunc(s string, f func(rune) bool) string
- func TrimPrefix(s, prefix string) string
- func TrimRight(s, 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) Cap() int
- 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 (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
Examples ¶
- Builder
- Clone
- Compare
- Contains
- ContainsAny
- ContainsFunc
- ContainsRune
- Count
- Cut
- CutPrefix
- CutSuffix
- EqualFold
- Fields
- FieldsFunc
- FieldsFuncSeq
- FieldsSeq
- HasPrefix
- HasSuffix
- Index
- IndexAny
- IndexByte
- IndexFunc
- IndexRune
- Join
- LastIndex
- LastIndexAny
- LastIndexByte
- LastIndexFunc
- Lines
- Map
- NewReplacer
- Repeat
- Replace
- ReplaceAll
- Split
- SplitAfter
- SplitAfterN
- SplitAfterSeq
- SplitN
- SplitSeq
- Title
- ToLower
- ToLowerSpecial
- ToTitle
- ToTitleSpecial
- ToUpper
- ToUpperSpecial
- ToValidUTF8
- Trim
- TrimFunc
- TrimLeft
- TrimLeftFunc
- TrimPrefix
- TrimRight
- TrimRightFunc
- TrimSpace
- TrimSuffix
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Clone ¶ added in go1.18
Clone returns a fresh copy of s. It guarantees to make a copy of s into a new allocation, which can be important when retaining only a small substring of a much larger string. Using Clone can help such programs use less memory. Of course, since using Clone makes a copy, overuse of Clone can make programs use more memory. Clone should typically be used only rarely, and only when profiling indicates that it is needed. For strings of length zero the string "" will be returned and no allocation is made.
Example ¶
package main
import (
"fmt"
"strings"
"unsafe"
)
func main() {
s := "abc"
clone := strings.Clone(s)
fmt.Println(s == clone)
fmt.Println(unsafe.StringData(s) == unsafe.StringData(clone))
}
Output: true false
func Compare ¶ added in go1.5
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.
Use Compare when you need to perform a three-way comparison (with slices.SortFunc, for example). It is usually clearer and always faster to use the built-in string comparison operators ==, <, >, and so on.
Example ¶
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"))
}
Output: -1 0 1
func Contains ¶
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("", ""))
}
Output: true false true true
func ContainsAny ¶
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("fail", "ui"))
fmt.Println(strings.ContainsAny("ure", "ui"))
fmt.Println(strings.ContainsAny("failure", "ui"))
fmt.Println(strings.ContainsAny("foo", ""))
fmt.Println(strings.ContainsAny("", ""))
}
Output: false true true true false false
func ContainsFunc ¶ added in go1.21.0
ContainsFunc reports whether any Unicode code points r within s satisfy f(r). It stops as soon as a call to f returns true.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
f := func(r rune) bool {
return r == 'a' || r == 'e' || r == 'i' || r == 'o' || r == 'u'
}
fmt.Println(strings.ContainsFunc("hello", f))
fmt.Println(strings.ContainsFunc("rhythms", f))
}
Output: true false
func ContainsRune ¶
ContainsRune reports whether the Unicode code point r is within s.
Example ¶
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))
}
Output: true false
func Count ¶
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 ¶
package main
import (
"fmt"
"strings"
)
func main() {
fmt.Println(strings.Count("cheese", "e"))
fmt.Println(strings.Count("five", "")) // before & after each rune
}
Output: 3 5
func Cut ¶ added in go1.18
Cut slices s around the first instance of sep, returning the text before and after sep. The found result reports whether sep appears in s. If sep does not appear in s, cut returns s, "", false.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
show := func(s, sep string) {
before, after, found := strings.Cut(s, sep)
fmt.Printf("Cut(%q, %q) = %q, %q, %v\n", s, sep, before, after, found)
}
show("Gopher", "Go")
show("Gopher", "ph")
show("Gopher", "er")
show("Gopher", "Badger")
}
Output: Cut("Gopher", "Go") = "", "pher", true Cut("Gopher", "ph") = "Go", "er", true Cut("Gopher", "er") = "Goph", "", true Cut("Gopher", "Badger") = "Gopher", "", false
func CutLast ¶ added in go1.27.0
CutLast slices s around the last instance of sep, returning the text before and after sep. The found result reports whether sep appears in s. If sep does not appear in s, CutLast returns s, "", false.
func CutPrefix ¶ added in go1.20
CutPrefix returns s without the provided leading prefix string and reports whether it found the prefix. If s doesn't start with prefix, CutPrefix returns s, false. If prefix is the empty string, CutPrefix returns s, true.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
show := func(s, prefix string) {
after, found := strings.CutPrefix(s, prefix)
fmt.Printf("CutPrefix(%q, %q) = %q, %v\n", s, prefix, after, found)
}
show("Gopher", "Go")
show("Gopher", "ph")
}
Output: CutPrefix("Gopher", "Go") = "pher", true CutPrefix("Gopher", "ph") = "Gopher", false
func CutSuffix ¶ added in go1.20
CutSuffix returns s without the provided ending suffix string and reports whether it found the suffix. If s doesn't end with suffix, CutSuffix returns s, false. If suffix is the empty string, CutSuffix returns s, true.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
show := func(s, suffix string) {
before, found := strings.CutSuffix(s, suffix)
fmt.Printf("CutSuffix(%q, %q) = %q, %v\n", s, suffix, before, found)
}
show("Gopher", "Go")
show("Gopher", "er")
}
Output: CutSuffix("Gopher", "Go") = "Gopher", false CutSuffix("Gopher", "er") = "Goph", true
func EqualFold ¶
EqualFold reports whether s and t, interpreted as UTF-8 strings, are equal under simple Unicode case-folding, which is a more general form of case-insensitivity.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
fmt.Println(strings.EqualFold("Go", "go"))
fmt.Println(strings.EqualFold("AB", "ab")) // true because comparison uses simple case-folding
fmt.Println(strings.EqualFold("ß", "ss")) // false because comparison does not use full case-folding
}
Output: true true false
func Fields ¶
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. Every element of the returned slice is non-empty. Unlike Split, leading and trailing runs of white space characters are discarded.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
fmt.Printf("Fields are: %q", strings.Fields(" foo bar baz "))
}
Output: Fields are: ["foo" "bar" "baz"]
func FieldsFunc ¶
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. Every element of the returned slice is non-empty. Unlike Split, leading and trailing runs of code points satisfying f(c) are discarded.
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.
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))
}
Output: Fields are: ["foo1" "bar2" "baz3"]
func FieldsFuncSeq ¶ added in go1.24.0
FieldsFuncSeq returns an iterator over substrings of s split around runs of Unicode code points satisfying f(c). The iterator yields the same strings that would be returned by FieldsFunc(s), but without constructing the slice.
Example ¶
package main
import (
"fmt"
"strings"
"unicode"
)
func main() {
text := "The quick brown fox"
fmt.Println("Split on whitespace(similar to FieldsSeq):")
for word := range strings.FieldsFuncSeq(text, unicode.IsSpace) {
fmt.Printf("%q\n", word)
}
mixedText := "abc123def456ghi"
fmt.Println("\nSplit on digits:")
for word := range strings.FieldsFuncSeq(mixedText, unicode.IsDigit) {
fmt.Printf("%q\n", word)
}
}
Output: Split on whitespace(similar to FieldsSeq): "The" "quick" "brown" "fox" Split on digits: "abc" "def" "ghi"
func FieldsSeq ¶ added in go1.24.0
FieldsSeq returns an iterator over substrings of s split around runs of whitespace characters, as defined by unicode.IsSpace. The iterator yields the same strings that would be returned by Fields(s), but without constructing the slice.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
text := "The quick brown fox"
fmt.Println("Split string into fields:")
for word := range strings.FieldsSeq(text) {
fmt.Printf("%q\n", word)
}
textWithSpaces := " lots of spaces "
fmt.Println("\nSplit string with multiple spaces:")
for word := range strings.FieldsSeq(textWithSpaces) {
fmt.Printf("%q\n", word)
}
}
Output: Split string into fields: "The" "quick" "brown" "fox" Split string with multiple spaces: "lots" "of" "spaces"
func HasPrefix ¶
HasPrefix reports 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", ""))
}
Output: true false true
func HasSuffix ¶
HasSuffix reports 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", ""))
}
Output: true false false true
func Index ¶
Index returns the index of the first instance of substr in s, or -1 if substr 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"))
}
Output: 4 -1
func IndexAny ¶
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"))
}
Output: 2 -1
func IndexByte ¶ added in go1.2
IndexByte returns the index of the first instance of c in s, or -1 if c is not present in s.
Example ¶
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'))
}
Output: 0 3 -1
func IndexFunc ¶
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))
}
Output: 7 -1
func IndexRune ¶
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'))
}
Output: 4 -1
func Join ¶
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.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
s := []string{"foo", "bar", "baz"}
fmt.Println(strings.Join(s, ", "))
}
Output: foo, bar, baz
func LastIndex ¶
LastIndex returns the index of the last instance of substr in s, or -1 if substr 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"))
}
Output: 0 3 -1
func LastIndexAny ¶
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 ¶
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"))
}
Output: 4 8 -1
func LastIndexByte ¶ added in go1.5
LastIndexByte returns the index of the last instance of c in s, or -1 if c is not present in s.
Example ¶
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'))
}
Output: 10 8 -1
func LastIndexFunc ¶
LastIndexFunc returns the index into s of the last Unicode code point satisfying f(c), or -1 if none do.
Example ¶
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))
}
Output: 5 2 -1
func Lines ¶ added in go1.24.0
Lines returns an iterator over the newline-terminated lines in the string s. The lines yielded by the iterator include their terminating newlines. If s is empty, the iterator yields no lines at all. If s does not end in a newline, the final yielded line will not end in a newline. It returns a single-use iterator.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
text := "Hello\nWorld\nGo Programming\n"
for line := range strings.Lines(text) {
fmt.Printf("%q\n", line)
}
}
Output: "Hello\n" "World\n" "Go Programming\n"
func Map ¶
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..."))
}
Output: 'Gjnf oevyyvt naq gur fyvgul tbcure...
func Repeat ¶
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))
}
Output: banana
func Replace ¶
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))
}
Output: oinky oinky oink moo moo moo
func ReplaceAll ¶ added in go1.12
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.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
fmt.Println(strings.ReplaceAll("oink oink oink", "oink", "moo"))
}
Output: moo moo moo
func Split ¶
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.
To split around the first instance of a separator, see Cut.
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"))
}
Output: ["a" "b" "c"] ["" "man " "plan " "canal panama"] [" " "x" "y" "z" " "] [""]
func SplitAfter ¶
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 ¶
package main
import (
"fmt"
"strings"
)
func main() {
fmt.Printf("%q\n", strings.SplitAfter("a,b,c", ","))
}
Output: ["a," "b," "c"]
func SplitAfterN ¶
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 ¶
package main
import (
"fmt"
"strings"
)
func main() {
fmt.Printf("%q\n", strings.SplitAfterN("a,b,c", ",", 2))
}
Output: ["a," "b,c"]
func SplitAfterSeq ¶ added in go1.24.0
SplitAfterSeq returns an iterator over substrings of s split after each instance of sep. The iterator yields the same strings that would be returned by SplitAfter(s, sep), but without constructing the slice. It returns a single-use iterator.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
s := "a,b,c,d"
for part := range strings.SplitAfterSeq(s, ",") {
fmt.Printf("%q\n", part)
}
}
Output: "a," "b," "c," "d"
func SplitN ¶
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.
To split around the first instance of a separator, see Cut.
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)
}
Output: ["a" "b,c"] [] (nil = true)
func SplitSeq ¶ added in go1.24.0
SplitSeq returns an iterator over all substrings of s separated by sep. The iterator yields the same strings that would be returned by Split(s, sep), but without constructing the slice. It returns a single-use iterator.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
s := "a,b,c,d"
for part := range strings.SplitSeq(s, ",") {
fmt.Printf("%q\n", part)
}
}
Output: "a" "b" "c" "d"
func Title
deprecated
Title returns a copy of the string s with all Unicode letters that begin words mapped to their Unicode title case.
Deprecated: The rule Title uses for word boundaries does not handle Unicode punctuation properly. Use golang.org/x/text/cases instead.
Example ¶
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("брат"))
}
Output: Her Royal Highness Loud Noises Брат
func ToLower ¶
ToLower returns s with all Unicode letters mapped to their lower case.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
fmt.Println(strings.ToLower("Gopher"))
}
Output: 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 using the case mapping specified by c.
Example ¶
package main
import (
"fmt"
"strings"
"unicode"
)
func main() {
fmt.Println(strings.ToLowerSpecial(unicode.TurkishCase, "Örnek İş"))
}
Output: örnek iş
func ToTitle ¶
ToTitle returns a copy of the string s with all Unicode letters mapped to their Unicode title case.
Example ¶
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("брат"))
}
Output: HER ROYAL HIGHNESS LOUD NOISES БРАТ
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 Unicode title case, giving priority to the special casing rules.
Example ¶
package main
import (
"fmt"
"strings"
"unicode"
)
func main() {
fmt.Println(strings.ToTitleSpecial(unicode.TurkishCase, "dünyanın ilk borsa yapısı Aizonai kabul edilir"))
}
Output: DÜNYANIN İLK BORSA YAPISI AİZONAİ KABUL EDİLİR
func ToUpper ¶
ToUpper returns s with all Unicode letters mapped to their upper case.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
fmt.Println(strings.ToUpper("Gopher"))
}
Output: 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 using the case mapping specified by c.
Example ¶
package main
import (
"fmt"
"strings"
"unicode"
)
func main() {
fmt.Println(strings.ToUpperSpecial(unicode.TurkishCase, "örnek iş"))
}
Output: ÖRNEK İŞ
func ToValidUTF8 ¶ added in go1.13
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.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
fmt.Printf("%s\n", strings.ToValidUTF8("abc", "\uFFFD"))
fmt.Printf("%s\n", strings.ToValidUTF8("a\xffb\xC0\xAFc\xff", ""))
fmt.Printf("%s\n", strings.ToValidUTF8("\xed\xa0\x80", "abc"))
}
Output: abc abc abc
func Trim ¶
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.Print(strings.Trim("¡¡¡Hello, Gophers!!!", "!¡"))
}
Output: Hello, Gophers
func TrimFunc ¶
TrimFunc returns a slice of the string s with all leading and trailing Unicode code points c satisfying f(c) removed.
Example ¶
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)
}))
}
Output: Hello, Gophers
func TrimLeft ¶
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.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
fmt.Print(strings.TrimLeft("¡¡¡Hello, Gophers!!!", "!¡"))
}
Output: Hello, Gophers!!!
func TrimLeftFunc ¶
TrimLeftFunc returns a slice of the string s with all leading Unicode code points c satisfying f(c) removed.
Example ¶
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)
}))
}
Output: Hello, Gophers!!!
func TrimPrefix ¶ added in go1.1
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 = "¡¡¡Hello, Gophers!!!"
s = strings.TrimPrefix(s, "¡¡¡Hello, ")
s = strings.TrimPrefix(s, "¡¡¡Howdy, ")
fmt.Print(s)
}
Output: Gophers!!!
func TrimRight ¶
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.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
fmt.Print(strings.TrimRight("¡¡¡Hello, Gophers!!!", "!¡"))
}
Output: ¡¡¡Hello, Gophers
func TrimRightFunc ¶
TrimRightFunc returns a slice of the string s with all trailing Unicode code points c satisfying f(c) removed.
Example ¶
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)
}))
}
Output: ¡¡¡Hello, Gophers
func TrimSpace ¶
TrimSpace returns a slice (substring) 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 Hello, Gophers \n\t\r\n"))
}
Output: Hello, Gophers
func TrimSuffix ¶ added in go1.1
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, Gophers!!!"
s = strings.TrimSuffix(s, ", Gophers!!!")
s = strings.TrimSuffix(s, ", Marmots!!!")
fmt.Print(s)
}
Output: ¡¡¡Hello
Types ¶
type Builder ¶ added in go1.10
type Builder struct {
// contains filtered or unexported fields
}
A Builder is used to efficiently build a string using Builder.Write methods. It minimizes memory copying. The zero value is ready to use. Do not copy a non-zero Builder.
Example ¶
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())
}
Output: 3...2...1...ignition
func (*Builder) Cap ¶ added in go1.12
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.
func (*Builder) Grow ¶ added in go1.10
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 ¶ added in go1.10
Len returns the number of accumulated bytes; b.Len() == len(b.String()).
func (*Builder) Reset ¶ added in go1.10
func (b *Builder) Reset()
Reset resets the Builder to be empty.
func (*Builder) Write ¶ added in go1.10
Write appends the contents of p to b's buffer. Write always returns len(p), nil.
func (*Builder) WriteByte ¶ added in go1.10
WriteByte appends the byte c to b's buffer. The returned error is always nil.
type Reader ¶
type Reader struct {
// contains filtered or unexported fields
}
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.
func NewReader ¶
NewReader returns a new Reader reading from s. It is similar to bytes.NewBufferString but more efficient and non-writable.
func (*Reader) ReadAt ¶
ReadAt implements the io.ReaderAt interface.
func (*Reader) ReadByte ¶
ReadByte implements the io.ByteReader interface.
func (*Reader) ReadRune ¶
ReadRune implements the io.RuneReader interface.
func (*Reader) Size ¶ added in go1.5
Size returns the original length of the underlying string. Size is the number of bytes available for reading via Reader.ReadAt. The returned value is always the same and is not affected by calls to any other method.
func (*Reader) UnreadByte ¶
UnreadByte implements the io.ByteScanner interface.
func (*Reader) UnreadRune ¶
UnreadRune implements the io.RuneScanner 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 ¶
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.
Example ¶
package main
import (
"fmt"
"strings"
)
func main() {
r := strings.NewReplacer("<", "<", ">", ">")
fmt.Println(r.Replace("This is <b>HTML</b>!"))
}
Output: This is <b>HTML</b>!
Source Files