Namespace: go.std.strconv

v1.0

Contents

• Summary
• Index
• Constants
• Variables
• Functions, Macros, and Special Forms
• Types

Summary

Provides a low-level interface to the strconv package.

Package strconv implements conversions to and from string representations
of basic data types.

# Numeric Conversions

The most common numeric conversions are Atoi (string to int) and Itoa (int to string).

i, err := strconv.Atoi("-42")
s := strconv.Itoa(-42)

These assume decimal and the Go int type.

ParseBool, ParseFloat, ParseInt, and ParseUint convert strings to values:

b, err := strconv.ParseBool("true")
f, err := strconv.ParseFloat("3.1415", 64)
i, err := strconv.ParseInt("-42", 10, 64)
u, err := strconv.ParseUint("42", 10, 64)

The parse functions return the widest type (float64, int64, and uint64),
but if the size argument specifies a narrower width the result can be
converted to that narrower type without data loss:

s := "2147483647" // biggest int32
i64, err := strconv.ParseInt(s, 10, 32)
...
i := int32(i64)

FormatBool, FormatFloat, FormatInt, and FormatUint convert values to strings:

s := strconv.FormatBool(true)
s := strconv.FormatFloat(3.1415, 'E', -1, 64)
s := strconv.FormatInt(-42, 16)
s := strconv.FormatUint(42, 16)

AppendBool, AppendFloat, AppendInt, and AppendUint are similar but
append the formatted value to a destination slice.

# String Conversions

Quote and QuoteToASCII convert strings to quoted Go string literals.
The latter guarantees that the result is an ASCII string, by escaping
any non-ASCII Unicode with \u:

q := strconv.Quote("Hello, 世界")
q := strconv.QuoteToASCII("Hello, 世界")

QuoteRune and QuoteRuneToASCII are similar but accept runes and
return quoted Go rune literals.

Unquote and UnquoteChar unquote Go string and rune literals.

Index

• *NumError
• AppendBool
• AppendFloat
• AppendInt
• AppendQuote
• AppendQuoteRune
• AppendQuoteRuneToASCII
• AppendQuoteRuneToGraphic
• AppendQuoteToASCII
• AppendQuoteToGraphic
• AppendUint
• Atoi
• CanBackquote
• ErrRange
• ErrSyntax
• FormatBool
• FormatFloat
• FormatInt
• FormatUint
• IntSize
• IsGraphic
• IsPrint
• Itoa
• NumError
• ParseBool
• ParseFloat
• ParseInt
• ParseUint
• Quote
• QuoteRune
• QuoteRuneToASCII
• QuoteRuneToGraphic
• QuoteToASCII
• QuoteToGraphic
• QuotedPrefix
• Unquote
• UnquoteChar
• arrayOfNumError

Legend

Constant Variable Function Macro Special form Type GoVar Receiver/Method

Constants

Constants are variables with :const true in their metadata. Joker currently does not recognize them as special; as such, it allows redefining them or their values.

• IntSize

  Int v1.0

  IntSize is the size in bits of an int or uint value.
  

Variables

• ErrRange

  Var v1.0

  ErrRange indicates that a value is out of range for the target type.
  

• ErrSyntax

  Var v1.0

  ErrSyntax indicates that a value does not have the right syntax for the target type.
  

Functions, Macros, and Special Forms

• AppendBool

  Function v1.0

  (AppendBool dst b)
  

  AppendBool appends "true" or "false", according to the value of b,
  to dst and returns the extended buffer.
  
  Go input arguments: (dst []byte, b bool)
  
  Go returns: []byte
  
  Joker input arguments: [^arrayOfByte dst, ^Boolean b]
  
  Joker returns: ^arrayOfByte

• AppendFloat

  Function v1.0

  (AppendFloat dst f fmt prec bitSize)
  

  AppendFloat appends the string form of the floating-point number f,
  as generated by FormatFloat, to dst and returns the extended buffer.
  
  Go input arguments: (dst []byte, f float64, fmt byte, prec int, bitSize int)
  
  Go returns: []byte
  
  Joker input arguments: [^arrayOfByte dst, ^Double f, ^Byte fmt, ^Int prec, ^Int bitSize]
  
  Joker returns: ^arrayOfByte

• AppendInt

  Function v1.0

  (AppendInt dst i base)
  

  AppendInt appends the string form of the integer i,
  as generated by FormatInt, to dst and returns the extended buffer.
  
  Go input arguments: (dst []byte, i int64, base int)
  
  Go returns: []byte
  
  Joker input arguments: [^arrayOfByte dst, ^BigInt i, ^Int base]
  
  Joker returns: ^arrayOfByte

• AppendQuote

  Function v1.0

  (AppendQuote dst s)
  

  AppendQuote appends a double-quoted Go string literal representing s,
  as generated by Quote, to dst and returns the extended buffer.
  
  Go input arguments: (dst []byte, s string)
  
  Go returns: []byte
  
  Joker input arguments: [^arrayOfByte dst, ^String s]
  
  Joker returns: ^arrayOfByte

• AppendQuoteRune

  Function v1.0

  (AppendQuoteRune dst r)
  

  AppendQuoteRune appends a single-quoted Go character literal representing the rune,
  as generated by QuoteRune, to dst and returns the extended buffer.
  
  Go input arguments: (dst []byte, r rune)
  
  Go returns: []byte
  
  Joker input arguments: [^arrayOfByte dst, ^Char r]
  
  Joker returns: ^arrayOfByte

• AppendQuoteRuneToASCII

  Function v1.0

  (AppendQuoteRuneToASCII dst r)
  

  AppendQuoteRuneToASCII appends a single-quoted Go character literal representing the rune,
  as generated by QuoteRuneToASCII, to dst and returns the extended buffer.
  
  Go input arguments: (dst []byte, r rune)
  
  Go returns: []byte
  
  Joker input arguments: [^arrayOfByte dst, ^Char r]
  
  Joker returns: ^arrayOfByte

• AppendQuoteRuneToGraphic

  Function v1.0

  (AppendQuoteRuneToGraphic dst r)
  

  AppendQuoteRuneToGraphic appends a single-quoted Go character literal representing the rune,
  as generated by QuoteRuneToGraphic, to dst and returns the extended buffer.
  
  Go input arguments: (dst []byte, r rune)
  
  Go returns: []byte
  
  Joker input arguments: [^arrayOfByte dst, ^Char r]
  
  Joker returns: ^arrayOfByte

• AppendQuoteToASCII

  Function v1.0

  (AppendQuoteToASCII dst s)
  

  AppendQuoteToASCII appends a double-quoted Go string literal representing s,
  as generated by QuoteToASCII, to dst and returns the extended buffer.
  
  Go input arguments: (dst []byte, s string)
  
  Go returns: []byte
  
  Joker input arguments: [^arrayOfByte dst, ^String s]
  
  Joker returns: ^arrayOfByte

• AppendQuoteToGraphic

  Function v1.0

  (AppendQuoteToGraphic dst s)
  

  AppendQuoteToGraphic appends a double-quoted Go string literal representing s,
  as generated by QuoteToGraphic, to dst and returns the extended buffer.
  
  Go input arguments: (dst []byte, s string)
  
  Go returns: []byte
  
  Joker input arguments: [^arrayOfByte dst, ^String s]
  
  Joker returns: ^arrayOfByte

• AppendUint

  Function v1.0

  (AppendUint dst i base)
  

  AppendUint appends the string form of the unsigned integer i,
  as generated by FormatUint, to dst and returns the extended buffer.
  
  Go input arguments: (dst []byte, i uint64, base int)
  
  Go returns: []byte
  
  Joker input arguments: [^arrayOfByte dst, ^Number i, ^Int base]
  
  Joker returns: ^arrayOfByte

• Atoi

  Function v1.0

  (Atoi s)
  

  Atoi is equivalent to ParseInt(s, 10, 0), converted to type int.
  
  Go input arguments: (s string)
  
  Go returns: (int, error)
  
  Joker input arguments: [^String s]
  
  Joker returns: [^Int, ^Error]

• CanBackquote

  Function v1.0

  (CanBackquote s)
  

  CanBackquote reports whether the string s can be represented
  unchanged as a single-line backquoted string without control
  characters other than tab.
  
  Go input arguments: (s string)
  
  Go returns: bool
  
  Joker input arguments: [^String s]
  
  Joker returns: ^Boolean

• FormatBool

  Function v1.0

  (FormatBool b)
  

  FormatBool returns "true" or "false" according to the value of b.
  
  Go input arguments: (b bool)
  
  Go returns: string
  
  Joker input arguments: [^Boolean b]
  
  Joker returns: ^String

• FormatFloat

  Function v1.0

  (FormatFloat f fmt prec bitSize)
  

  FormatFloat converts the floating-point number f to a string,
  according to the format fmt and precision prec. It rounds the
  result assuming that the original was obtained from a floating-point
  value of bitSize bits (32 for float32, 64 for float64).
  
  The format fmt is one of
  'b' (-ddddp±ddd, a binary exponent),
  'e' (-d.dddde±dd, a decimal exponent),
  'E' (-d.ddddE±dd, a decimal exponent),
  'f' (-ddd.dddd, no exponent),
  'g' ('e' for large exponents, 'f' otherwise),
  'G' ('E' for large exponents, 'f' otherwise),
  'x' (-0xd.ddddp±ddd, a hexadecimal fraction and binary exponent), or
  'X' (-0Xd.ddddP±ddd, a hexadecimal fraction and binary exponent).
  
  The precision prec controls the number of digits (excluding the exponent)
  printed by the 'e', 'E', 'f', 'g', 'G', 'x', and 'X' formats.
  For 'e', 'E', 'f', 'x', and 'X', it is the number of digits after the decimal point.
  For 'g' and 'G' it is the maximum number of significant digits (trailing
  zeros are removed).
  The special precision -1 uses the smallest number of digits
  necessary such that ParseFloat will return f exactly.
  
  Go input arguments: (f float64, fmt byte, prec int, bitSize int)
  
  Go returns: string
  
  Joker input arguments: [^Double f, ^Byte fmt, ^Int prec, ^Int bitSize]
  
  Joker returns: ^String

• FormatInt

  Function v1.0

  (FormatInt i base)
  

  FormatInt returns the string representation of i in the given base,
  for 2 <= base <= 36. The result uses the lower-case letters 'a' to 'z'
  for digit values >= 10.
  
  Go input arguments: (i int64, base int)
  
  Go returns: string
  
  Joker input arguments: [^BigInt i, ^Int base]
  
  Joker returns: ^String

• FormatUint

  Function v1.0

  (FormatUint i base)
  

  FormatUint returns the string representation of i in the given base,
  for 2 <= base <= 36. The result uses the lower-case letters 'a' to 'z'
  for digit values >= 10.
  
  Go input arguments: (i uint64, base int)
  
  Go returns: string
  
  Joker input arguments: [^Number i, ^Int base]
  
  Joker returns: ^String

• IsGraphic

  Function v1.0

  (IsGraphic r)
  

  IsGraphic reports whether the rune is defined as a Graphic by Unicode. Such
  characters include letters, marks, numbers, punctuation, symbols, and
  spaces, from categories L, M, N, P, S, and Zs.
  
  Go input arguments: (r rune)
  
  Go returns: bool
  
  Joker input arguments: [^Char r]
  
  Joker returns: ^Boolean

• IsPrint

  Function v1.0

  (IsPrint r)
  

  IsPrint reports whether the rune is defined as printable by Go, with
  the same definition as unicode.IsPrint: letters, numbers, punctuation,
  symbols and ASCII space.
  
  Go input arguments: (r rune)
  
  Go returns: bool
  
  Joker input arguments: [^Char r]
  
  Joker returns: ^Boolean

• Itoa

  Function v1.0

  (Itoa i)
  

  Itoa is equivalent to FormatInt(int64(i), 10).
  
  Go input arguments: (i int)
  
  Go returns: string
  
  Joker input arguments: [^Int i]
  
  Joker returns: ^String

• ParseBool

  Function v1.0

  (ParseBool str)
  

  ParseBool returns the boolean value represented by the string.
  It accepts 1, t, T, TRUE, true, True, 0, f, F, FALSE, false, False.
  Any other value returns an error.
  
  Go input arguments: (str string)
  
  Go returns: (bool, error)
  
  Joker input arguments: [^String str]
  
  Joker returns: [^Boolean, ^Error]

• ParseFloat

  Function v1.0

  (ParseFloat s bitSize)
  

  ParseFloat converts the string s to a floating-point number
  with the precision specified by bitSize: 32 for float32, or 64 for float64.
  When bitSize=32, the result still has type float64, but it will be
  convertible to float32 without changing its value.
  
  ParseFloat accepts decimal and hexadecimal floating-point numbers
  as defined by the Go syntax for [floating-point literals].
  If s is well-formed and near a valid floating-point number,
  ParseFloat returns the nearest floating-point number rounded
  using IEEE754 unbiased rounding.
  (Parsing a hexadecimal floating-point value only rounds when
  there are more bits in the hexadecimal representation than
  will fit in the mantissa.)
  
  The errors that ParseFloat returns have concrete type *NumError
  and include err.Num = s.
  
  If s is not syntactically well-formed, ParseFloat returns err.Err = ErrSyntax.
  
  If s is syntactically well-formed but is more than 1/2 ULP
  away from the largest floating point number of the given size,
  ParseFloat returns f = ±Inf, err.Err = ErrRange.
  
  ParseFloat recognizes the string "NaN", and the (possibly signed) strings "Inf" and "Infinity"
  as their respective special floating point values. It ignores case when matching.
  
  [floating-point literals]: https://go.dev/ref/spec#Floating-point_literals
  
  Go input arguments: (s string, bitSize int)
  
  Go returns: (float64, error)
  
  Joker input arguments: [^String s, ^Int bitSize]
  
  Joker returns: [^Double, ^Error]

• ParseInt

  Function v1.0

  (ParseInt s base bitSize)
  

  ParseInt interprets a string s in the given base (0, 2 to 36) and
  bit size (0 to 64) and returns the corresponding value i.
  
  The string may begin with a leading sign: "+" or "-".
  
  If the base argument is 0, the true base is implied by the string's
  prefix following the sign (if present): 2 for "0b", 8 for "0" or "0o",
  16 for "0x", and 10 otherwise. Also, for argument base 0 only,
  underscore characters are permitted as defined by the Go syntax for
  [integer literals].
  
  The bitSize argument specifies the integer type
  that the result must fit into. Bit sizes 0, 8, 16, 32, and 64
  correspond to int, int8, int16, int32, and int64.
  If bitSize is below 0 or above 64, an error is returned.
  
  The errors that ParseInt returns have concrete type *NumError
  and include err.Num = s. If s is empty or contains invalid
  digits, err.Err = ErrSyntax and the returned value is 0;
  if the value corresponding to s cannot be represented by a
  signed integer of the given size, err.Err = ErrRange and the
  returned value is the maximum magnitude integer of the
  appropriate bitSize and sign.
  
  [integer literals]: https://go.dev/ref/spec#Integer_literals
  
  Go input arguments: (s string, base int, bitSize int)
  
  Go returns: (i int64, err error)
  
  Joker input arguments: [^String s, ^Int base, ^Int bitSize]
  
  Joker returns: [^BigInt i, ^Error err]

• ParseUint

  Function v1.0

  (ParseUint s base bitSize)
  

  ParseUint is like ParseInt but for unsigned numbers.
  
  A sign prefix is not permitted.
  
  Go input arguments: (s string, base int, bitSize int)
  
  Go returns: (uint64, error)
  
  Joker input arguments: [^String s, ^Int base, ^Int bitSize]
  
  Joker returns: [^Number, ^Error]

• Quote

  Function v1.0

  (Quote s)
  

  Quote returns a double-quoted Go string literal representing s. The
  returned string uses Go escape sequences (\t, \n, \xFF, \u0100) for
  control characters and non-printable characters as defined by
  IsPrint.
  
  Go input arguments: (s string)
  
  Go returns: string
  
  Joker input arguments: [^String s]
  
  Joker returns: ^String

• QuoteRune

  Function v1.0

  (QuoteRune r)
  

  QuoteRune returns a single-quoted Go character literal representing the
  rune. The returned string uses Go escape sequences (\t, \n, \xFF, \u0100)
  for control characters and non-printable characters as defined by IsPrint.
  If r is not a valid Unicode code point, it is interpreted as the Unicode
  replacement character U+FFFD.
  
  Go input arguments: (r rune)
  
  Go returns: string
  
  Joker input arguments: [^Char r]
  
  Joker returns: ^String

• QuoteRuneToASCII

  Function v1.0

  (QuoteRuneToASCII r)
  

  QuoteRuneToASCII returns a single-quoted Go character literal representing
  the rune. The returned string uses Go escape sequences (\t, \n, \xFF,
  \u0100) for non-ASCII characters and non-printable characters as defined
  by IsPrint.
  If r is not a valid Unicode code point, it is interpreted as the Unicode
  replacement character U+FFFD.
  
  Go input arguments: (r rune)
  
  Go returns: string
  
  Joker input arguments: [^Char r]
  
  Joker returns: ^String

• QuoteRuneToGraphic

  Function v1.0

  (QuoteRuneToGraphic r)
  

  QuoteRuneToGraphic returns a single-quoted Go character literal representing
  the rune. If the rune is not a Unicode graphic character,
  as defined by IsGraphic, the returned string will use a Go escape sequence
  (\t, \n, \xFF, \u0100).
  If r is not a valid Unicode code point, it is interpreted as the Unicode
  replacement character U+FFFD.
  
  Go input arguments: (r rune)
  
  Go returns: string
  
  Joker input arguments: [^Char r]
  
  Joker returns: ^String

• QuoteToASCII

  Function v1.0

  (QuoteToASCII s)
  

  QuoteToASCII returns a double-quoted Go string literal representing s.
  The returned string uses Go escape sequences (\t, \n, \xFF, \u0100) for
  non-ASCII characters and non-printable characters as defined by IsPrint.
  
  Go input arguments: (s string)
  
  Go returns: string
  
  Joker input arguments: [^String s]
  
  Joker returns: ^String

• QuoteToGraphic

  Function v1.0

  (QuoteToGraphic s)
  

  QuoteToGraphic returns a double-quoted Go string literal representing s.
  The returned string leaves Unicode graphic characters, as defined by
  IsGraphic, unchanged and uses Go escape sequences (\t, \n, \xFF, \u0100)
  for non-graphic characters.
  
  Go input arguments: (s string)
  
  Go returns: string
  
  Joker input arguments: [^String s]
  
  Joker returns: ^String

• QuotedPrefix

  Function v1.0

  (QuotedPrefix s)
  

  QuotedPrefix returns the quoted string (as understood by Unquote) at the prefix of s.
  If s does not start with a valid quoted string, QuotedPrefix returns an error.
  
  Go input arguments: (s string)
  
  Go returns: (string, error)
  
  Joker input arguments: [^String s]
  
  Joker returns: [^String, ^Error]

• Unquote

  Function v1.0

  (Unquote s)
  

  Unquote interprets s as a single-quoted, double-quoted,
  or backquoted Go string literal, returning the string value
  that s quotes. (If s is single-quoted, it would be a Go
  character literal; Unquote returns the corresponding
  one-character string.)
  
  Go input arguments: (s string)
  
  Go returns: (string, error)
  
  Joker input arguments: [^String s]
  
  Joker returns: [^String, ^Error]

• UnquoteChar

  Function v1.0

  (UnquoteChar s quote)
  

  UnquoteChar decodes the first character or byte in the escaped string
  or character literal represented by the string s.
  It returns four values:
  
  1. value, the decoded Unicode code point or byte value;
  2. multibyte, a boolean indicating whether the decoded character requires a multibyte UTF-8 representation;
  3. tail, the remainder of the string after the character; and
  4. an error that will be nil if the character is syntactically valid.
  
  The second argument, quote, specifies the type of literal being parsed
  and therefore which escaped quote character is permitted.
  If set to a single quote, it permits the sequence \' and disallows unescaped '.
  If set to a double quote, it permits \" and disallows unescaped ".
  If set to zero, it does not permit either escape and allows both quote characters to appear unescaped.
  
  Go input arguments: (s string, quote byte)
  
  Go returns: (value rune, multibyte bool, tail string, err error)
  
  Joker input arguments: [^String s, ^Byte quote]
  
  Joker returns: [^Char value, ^Boolean multibyte, ^String tail, ^Error err]

Types

• *NumError

  Concrete Type v1.0

  A NumError records a failed conversion.
  

• Error

  Receiver for *NumError v1.0

  ([])
  

• Unwrap

  Receiver for *NumError v1.0

  ([])
  

• NumError

  Concrete Type v1.0

  A NumError records a failed conversion.
  

• arrayOfNumError

  Concrete Type v1.0

  A NumError records a failed conversion.