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Package strconv

import "strconv"
Overview
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Examples

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

Constants

const IntSize = intSize

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

Variables

var ErrRange = errors.New("value out of range")

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

var ErrSyntax = errors.New("invalid syntax")

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

func AppendBool

func AppendBool(dst []byte, b bool) []byte

AppendBool appends "true" or "false", according to the value of b, to dst and returns the extended buffer.

func AppendFloat

func AppendFloat(dst []byte, f float64, fmt byte, prec int, bitSize int) []byte

AppendFloat appends the string form of the floating-point number f, as generated by FormatFloat, to dst and returns the extended buffer.

func AppendInt

func AppendInt(dst []byte, i int64, base int) []byte

AppendInt appends the string form of the integer i, as generated by FormatInt, to dst and returns the extended buffer.

func AppendQuote

func AppendQuote(dst []byte, s string) []byte

AppendQuote appends a double-quoted Go string literal representing s, as generated by Quote, to dst and returns the extended buffer.

func AppendQuoteRune

func AppendQuoteRune(dst []byte, r rune) []byte

AppendQuoteRune appends a single-quoted Go character literal representing the rune, as generated by QuoteRune, to dst and returns the extended buffer.

func AppendQuoteRuneToASCII

func AppendQuoteRuneToASCII(dst []byte, r rune) []byte

AppendQuoteRuneToASCII appends a single-quoted Go character literal representing the rune, as generated by QuoteRuneToASCII, to dst and returns the extended buffer.

func AppendQuoteToASCII

func AppendQuoteToASCII(dst []byte, s string) []byte

AppendQuoteToASCII appends a double-quoted Go string literal representing s, as generated by QuoteToASCII, to dst and returns the extended buffer.

func AppendUint

func AppendUint(dst []byte, i uint64, base int) []byte

AppendUint appends the string form of the unsigned integer i, as generated by FormatUint, to dst and returns the extended buffer.

func Atoi

func Atoi(s string) (i int, err error)

Atoi is shorthand for ParseInt(s, 10, 0).

func CanBackquote

func CanBackquote(s string) bool

CanBackquote reports whether the string s can be represented unchanged as a single-line backquoted string without control characters other than tab.

func FormatBool

func FormatBool(b bool) string

FormatBool returns "true" or "false" according to the value of b

func FormatFloat

func FormatFloat(f float64, fmt byte, prec, bitSize int) string

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), or 'G' ('E' for large exponents, 'f' otherwise).

The precision prec controls the number of digits (excluding the exponent) printed by the 'e', 'E', 'f', 'g', and 'G' formats. For 'e', 'E', and 'f' it is the number of digits after the decimal point. For 'g' and 'G' it is the total number of digits. The special precision -1 uses the smallest number of digits necessary such that ParseFloat will return f exactly.

func FormatInt

func FormatInt(i int64, base int) string

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.

func FormatUint

func FormatUint(i uint64, base int) string

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.

func IsPrint

func IsPrint(r rune) bool

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.

func Itoa

func Itoa(i int) string

Itoa is shorthand for FormatInt(i, 10).

func ParseBool

func ParseBool(str string) (value bool, err error)

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.

func ParseFloat

func ParseFloat(s string, bitSize int) (f float64, err error)

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.

If s is well-formed and near a valid floating point number, ParseFloat returns the nearest floating point number rounded using IEEE754 unbiased rounding.

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.

func ParseInt

func ParseInt(s string, base int, bitSize int) (i int64, err error)

ParseInt interprets a string s in the given base (2 to 36) and returns the corresponding value i. If base == 0, the base is implied by the string's prefix: base 16 for "0x", base 8 for "0", and base 10 otherwise.

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.

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.

func ParseUint

func ParseUint(s string, base int, bitSize int) (n uint64, err error)

ParseUint is like ParseInt but for unsigned numbers.

func Quote

func Quote(s string) string

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.

func QuoteRune

func QuoteRune(r rune) string

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.

func QuoteRuneToASCII

func QuoteRuneToASCII(r rune) string

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.

func QuoteToASCII

func QuoteToASCII(s string) string

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.

func Unquote

func Unquote(s string) (t string, err error)

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.)

Example

Unquote("cafe\\u0301"): invalid syntax
Unquote("`cafe\\u0301`") = cafe\u0301
Unquote("\"cafe\\u0301\"") = café
Unquote("'\\u00e9'") = é

func UnquoteChar

func UnquoteChar(s string, quote byte) (value rune, multibyte bool, tail string, err error)

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.

type NumError

type NumError struct {
        Func string // the failing function (ParseBool, ParseInt, ParseUint, ParseFloat)
        Num  string // the input
        Err  error  // the reason the conversion failed (ErrRange, ErrSyntax)
}

A NumError records a failed conversion.

func (*NumError) Error

func (e *NumError) Error() string