Package strings
Overview ▹
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 ▹
Index ▾
Examples
(Expand All)
- Builder
- Compare
- Contains
- ContainsAny
- ContainsRune
- Count
- EqualFold
- Fields
- FieldsFunc
- HasPrefix
- HasSuffix
- Index
- IndexAny
- IndexByte
- IndexFunc
- IndexRune
- Join
- LastIndex
- LastIndexAny
- LastIndexByte
- LastIndexFunc
- Map
- NewReplacer
- Repeat
- Replace
- ReplaceAll
- Split
- SplitAfter
- SplitAfterN
- SplitN
- Title
- ToLower
- ToLowerSpecial
- ToTitle
- ToTitleSpecial
- ToUpper
- ToUpperSpecial
- Trim
- TrimFunc
- TrimLeft
- TrimLeftFunc
- TrimPrefix
- TrimRight
- TrimRightFunc
- TrimSpace
- TrimSuffix
Package files
builder.go compare.go reader.go replace.go search.go strings.go
func Compare 1.5
func Compare(a, b string) intCompare 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
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-1
0
1
func Contains
func Contains(s, substr string) boolContains reports whether substr is within s.
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true
false
true
true
func ContainsAny
func ContainsAny(s, chars string) boolContainsAny reports whether any Unicode code points in chars are within s.
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false
true
true
true
false
false
func ContainsRune
func ContainsRune(s string, r rune) boolContainsRune reports whether the Unicode code point r is within s.
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true
false
func Count
func Count(s, substr string) intCount 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.
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3
5
func EqualFold
func EqualFold(s, t string) boolEqualFold 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.
▹ Example
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true
func Fields
func Fields(s string) []stringFields 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.
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Fields are: ["foo" "bar" "baz"]
func FieldsFunc
func FieldsFunc(s string, f func(rune) bool) []stringFieldsFunc 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.
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Fields are: ["foo1" "bar2" "baz3"]
func HasPrefix
func HasPrefix(s, prefix string) boolHasPrefix tests whether the string s begins with prefix.
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true
false
true
func HasSuffix
func HasSuffix(s, suffix string) boolHasSuffix tests whether the string s ends with suffix.
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true
false
false
true
func Index
func Index(s, substr string) intIndex returns the index of the first instance of substr in s, or -1 if substr is not present in s.
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4
-1
func IndexAny
func IndexAny(s, chars string) intIndexAny 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.
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2
-1
func IndexByte 1.2
func IndexByte(s string, c byte) intIndexByte returns the index of the first instance of c in s, or -1 if c is not present in s.
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0
3
-1
func IndexFunc
func IndexFunc(s string, f func(rune) bool) intIndexFunc returns the index into s of the first Unicode code point satisfying f(c), or -1 if none do.
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7
-1
func IndexRune
func IndexRune(s string, r rune) intIndexRune 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.
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4
-1
func Join
func Join(elems []string, sep string) stringJoin concatenates the elements of its first argument to create a single string. The separator string sep is placed between elements in the resulting string.
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foo, bar, baz
func LastIndex
func LastIndex(s, substr string) intLastIndex returns the index of the last instance of substr in s, or -1 if substr is not present in s.
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0
3
-1
func LastIndexAny
func LastIndexAny(s, chars string) intLastIndexAny 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.
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4
8
-1
func LastIndexByte 1.5
func LastIndexByte(s string, c byte) intLastIndexByte returns the index of the last instance of c in s, or -1 if c is not present in s.
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10
8
-1
func LastIndexFunc
func LastIndexFunc(s string, f func(rune) bool) intLastIndexFunc returns the index into s of the last Unicode code point satisfying f(c), or -1 if none do.
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5
2
-1
func Map
func Map(mapping func(rune) rune, s string) stringMap 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.
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'Gjnf oevyyvt naq gur fyvgul tbcure...
func Repeat
func Repeat(s string, count int) stringRepeat 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.
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banana
func Replace
func Replace(s, old, new string, n int) stringReplace 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.
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oinky oinky oink
moo moo moo
func ReplaceAll 1.12
func ReplaceAll(s, old, new string) stringReplaceAll 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
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moo moo moo
func Split
func Split(s, sep string) []stringSplit 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
▾ Example
["a" "b" "c"]
["" "man " "plan " "canal panama"]
[" " "x" "y" "z" " "]
[""]
func SplitAfter
func SplitAfter(s, sep string) []stringSplitAfter 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
▾ Example
["a," "b," "c"]
func SplitAfterN
func SplitAfterN(s, sep string, n int) []stringSplitAfterN 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
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["a," "b,c"]
func SplitN
func SplitN(s, sep string, n int) []stringSplitN 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
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["a" "b,c"]
[] (nil = true)
func Title
func Title(s string) stringTitle 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.
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Her Royal Highness
Loud Noises
Хлеб
func ToLower
func ToLower(s string) stringToLower returns s with all Unicode letters mapped to their lower case.
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gopher
func ToLowerSpecial
func ToLowerSpecial(c unicode.SpecialCase, s string) stringToLowerSpecial returns a copy of the string s with all Unicode letters mapped to their lower case using the case mapping specified by c.
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önnek iş
func ToTitle
func ToTitle(s string) stringToTitle returns a copy of the string s with all Unicode letters mapped to their Unicode title case.
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HER ROYAL HIGHNESS
LOUD NOISES
ХЛЕБ
func ToTitleSpecial
func ToTitleSpecial(c unicode.SpecialCase, s string) stringToTitleSpecial returns a copy of the string s with all Unicode letters mapped to their Unicode title case, giving priority to the special casing rules.
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DÜNYANIN İLK BORSA YAPISI AİZONAİ KABUL EDİLİR
func ToUpper
func ToUpper(s string) stringToUpper returns s with all Unicode letters mapped to their upper case.
▹ Example
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GOPHER
func ToUpperSpecial
func ToUpperSpecial(c unicode.SpecialCase, s string) stringToUpperSpecial returns a copy of the string s with all Unicode letters mapped to their upper case using the case mapping specified by c.
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ÖRNEK İŞ
func ToValidUTF8 1.13
func ToValidUTF8(s, replacement string) stringToValidUTF8 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.
func Trim
func Trim(s, cutset string) stringTrim returns a slice of the string s with all leading and trailing Unicode code points contained in cutset removed.
▹ Example
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Hello, Gophers
func TrimFunc
func TrimFunc(s string, f func(rune) bool) stringTrimFunc returns a slice of the string s with all leading and trailing Unicode code points c satisfying f(c) removed.
▹ Example
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Hello, Gophers
func TrimLeft
func TrimLeft(s, cutset string) stringTrimLeft 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
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Hello, Gophers!!!
func TrimLeftFunc
func TrimLeftFunc(s string, f func(rune) bool) stringTrimLeftFunc returns a slice of the string s with all leading Unicode code points c satisfying f(c) removed.
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Hello, Gophers!!!
func TrimPrefix 1.1
func TrimPrefix(s, prefix string) stringTrimPrefix returns s without the provided leading prefix string. If s doesn't start with prefix, s is returned unchanged.
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Gophers!!!
func TrimRight
func TrimRight(s, cutset string) stringTrimRight 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
▾ Example
¡¡¡Hello, Gophers
func TrimRightFunc
func TrimRightFunc(s string, f func(rune) bool) stringTrimRightFunc returns a slice of the string s with all trailing Unicode code points c satisfying f(c) removed.
▹ Example
▾ Example
¡¡¡Hello, Gophers
func TrimSpace
func TrimSpace(s string) stringTrimSpace returns a slice of the string s, with all leading and trailing white space removed, as defined by Unicode.
▹ Example
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Hello, Gophers
func TrimSuffix 1.1
func TrimSuffix(s, suffix string) stringTrimSuffix returns s without the provided trailing suffix string. If s doesn't end with suffix, s is returned unchanged.
▹ Example
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¡¡¡Hello
type Builder 1.10
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
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3...2...1...ignition
func (*Builder) Cap 1.12
func (b *Builder) Cap() intCap 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 1.10
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 1.10
func (b *Builder) Len() intLen returns the number of accumulated bytes; b.Len() == len(b.String()).
func (*Builder) Reset 1.10
func (b *Builder) Reset()Reset resets the Builder to be empty.
func (*Builder) String 1.10
func (b *Builder) String() stringString returns the accumulated string.
func (*Builder) Write 1.10
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 1.10
func (b *Builder) WriteByte(c byte) errorWriteByte appends the byte c to b's buffer. The returned error is always nil.
func (*Builder) WriteRune 1.10
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 1.10
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.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.
type Reader struct {
// contains filtered or unexported fields
}
func NewReader
func NewReader(s string) *ReaderNewReader 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() intLen 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)Read implements the io.Reader interface.
func (*Reader) ReadAt
func (r *Reader) ReadAt(b []byte, off int64) (n int, err error)ReadAt implements the io.ReaderAt interface.
func (*Reader) ReadByte
func (r *Reader) ReadByte() (byte, error)ReadByte implements the io.ByteReader interface.
func (*Reader) ReadRune
func (r *Reader) ReadRune() (ch rune, size int, err error)ReadRune implements the io.RuneReader interface.
func (*Reader) Reset 1.7
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 1.5
func (r *Reader) Size() int64Size 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() errorUnreadByte implements the io.ByteScanner interface.
func (*Reader) UnreadRune
func (r *Reader) UnreadRune() errorUnreadRune implements the io.RuneScanner interface.
func (*Reader) WriteTo 1.1
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) *ReplacerNewReplacer 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
▾ Example
This is <b>HTML</b>!
func (*Replacer) Replace
func (r *Replacer) Replace(s string) stringReplace 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
- ☞
The rule Title uses for word boundaries does not handle Unicode punctuation properly.