strconv

func Atoi

1func Atoi(s string) (int, error)

Atoi is equivalent to ParseInt(s, 10, 0), converted to type int.

1v := "10"
2if s, err := strconv.Atoi(v); err == nil {
3	fmt.Printf("%T, %v", s, s)
4}

int, 10

func FormatBool

1func FormatBool(b bool) string

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

1v := true
2s := strconv.FormatBool(v)
3fmt.Printf("%T, %v\n", s, s)

string, true

func FormatFloat

1func 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), ‘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.

1v := 3.1415926535
2
3s32 := strconv.FormatFloat(v, 'E', -1, 32)
4fmt.Printf("%T, %v\n", s32, s32)
5
6s64 := strconv.FormatFloat(v, 'E', -1, 64)
7fmt.Printf("%T, %v\n", s64, s64)

string, 3.1415927E+00
string, 3.1415926535E+00

func FormatInt

1func 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.

1v := int64(-42)
2
3s10 := strconv.FormatInt(v, 10)
4fmt.Printf("%T, %v\n", s10, s10)
5
6s16 := strconv.FormatInt(v, 16)
7fmt.Printf("%T, %v\n", s16, s16)

string, -42
string, -2a

func FormatUint

1func 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.

1v := uint64(42)
2
3s10 := strconv.FormatUint(v, 10)
4fmt.Printf("%T, %v\n", s10, s10)
5
6s16 := strconv.FormatUint(v, 16)
7fmt.Printf("%T, %v\n", s16, s16)

string, 42
string, 2a

func Itoa

1func Itoa(i int) string

Itoa is equivalent to FormatInt(int64(i), 10).

1i := 10
2s := strconv.Itoa(i)
3fmt.Printf("%T, %v\n", s, s)

string, 10

func ParseBool

1func ParseBool(str string) (bool, 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.

1v := "true"
2if s, err := strconv.ParseBool(v); err == nil {
3	fmt.Printf("%T, %v\n", s, s)
4}

bool, true

func ParseFloat

1func ParseFloat(s string, bitSize int) (float64, 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.

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.

 1v := "3.1415926535"
 2if s, err := strconv.ParseFloat(v, 32); err == nil {
 3	fmt.Printf("%T, %v\n", s, s)
 4}
 5if s, err := strconv.ParseFloat(v, 64); err == nil {
 6	fmt.Printf("%T, %v\n", s, s)
 7}
 8if s, err := strconv.ParseFloat("NaN", 32); err == nil {
 9	fmt.Printf("%T, %v\n", s, s)
10}
11
12if s, err := strconv.ParseFloat("nan", 32); err == nil {
13	fmt.Printf("%T, %v\n", s, s)
14}
15if s, err := strconv.ParseFloat("inf", 32); err == nil {
16	fmt.Printf("%T, %v\n", s, s)
17}
18if s, err := strconv.ParseFloat("+Inf", 32); err == nil {
19	fmt.Printf("%T, %v\n", s, s)
20}
21if s, err := strconv.ParseFloat("-Inf", 32); err == nil {
22	fmt.Printf("%T, %v\n", s, s)
23}
24if s, err := strconv.ParseFloat("-0", 32); err == nil {
25	fmt.Printf("%T, %v\n", s, s)
26}
27if s, err := strconv.ParseFloat("+0", 32); err == nil {
28	fmt.Printf("%T, %v\n", s, s)
29}

float64, 3.1415927410125732
float64, 3.1415926535
float64, NaN
float64, NaN
float64, +Inf
float64, +Inf
float64, -Inf
float64, -0
float64, 0

func ParseInt

1func ParseInt(s string, base int, bitSize int) (i int64, err error)

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.

 1v32 := "-354634382"
 2if s, err := strconv.ParseInt(v32, 10, 32); err == nil {
 3	fmt.Printf("%T, %v\n", s, s)
 4}
 5if s, err := strconv.ParseInt(v32, 16, 32); err == nil {
 6	fmt.Printf("%T, %v\n", s, s)
 7}
 8
 9v64 := "-3546343826724305832"
10if s, err := strconv.ParseInt(v64, 10, 64); err == nil {
11	fmt.Printf("%T, %v\n", s, s)
12}
13if s, err := strconv.ParseInt(v64, 16, 64); err == nil {
14	fmt.Printf("%T, %v\n", s, s)
15}

int64, -354634382
int64, -3546343826724305832

func ParseUint

1func ParseUint(s string, base int, bitSize int) (uint64, error)

ParseUint is like ParseInt but for unsigned numbers.

A sign prefix is not permitted.

1v := "42"
2if s, err := strconv.ParseUint(v, 10, 32); err == nil {
3	fmt.Printf("%T, %v\n", s, s)
4}
5if s, err := strconv.ParseUint(v, 10, 64); err == nil {
6	fmt.Printf("%T, %v\n", s, s)
7}

uint64, 42
uint64, 42