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GO Time.Format用法及代码示例

GO语言"time"包中"Time.Format"类型的用法及代码示例。

用法:

func(t Time) Format(layout string) string

格式返回根据参数定义的布局格式化的时间值的文本表示。请参阅名为 Layout 的常量的文档以了解如何表示布局格式。

Time.Format 的可执行示例详细演示了布局字符串的工作原理,是一个很好的参考。

例子:

package main

import (
    "fmt"
    "time"
)

func main() {
    // Parse a time value from a string in the standard Unix format.
    t, err := time.Parse(time.UnixDate, "Wed Feb 25 11:06:39 PST 2015")
    if err != nil { // Always check errors even if they should not happen.
        panic(err)
    }

    // time.Time's Stringer method is useful without any format.
    fmt.Println("default format:", t)

    // Predefined constants in the package implement common layouts.
    fmt.Println("Unix format:", t.Format(time.UnixDate))

    // The time zone attached to the time value affects its output.
    fmt.Println("Same, in UTC:", t.UTC().Format(time.UnixDate))

    // The rest of this function demonstrates the properties of the
    // layout string used in the format.

    // The layout string used by the Parse function and Format method
    // shows by example how the reference time should be represented.
    // We stress that one must show how the reference time is formatted,
    // not a time of the user's choosing. Thus each layout string is a
    // representation of the time stamp,
    //	Jan 2 15:04:05 2006 MST
    // An easy way to remember this value is that it holds, when presented
    // in this order, the values (lined up with the elements above):
    //	  1 2  3  4  5    6  -7
    // There are some wrinkles illustrated below.

    // Most uses of Format and Parse use constant layout strings such as
    // the ones defined in this package, but the interface is flexible,
    // as these examples show.

    // Define a helper function to make the examples' output look nice.
    do := func(name, layout, want string) {
        got := t.Format(layout)
        if want != got {
            fmt.Printf("error: for %q got %q; expected %q\n", layout, got, want)
            return
        }
        fmt.Printf("%-16s %q gives %q\n", name, layout, got)
    }

    // Print a header in our output.
    fmt.Printf("\nFormats:\n\n")

    // Simple starter examples.
    do("Basic full date", "Mon Jan 2 15:04:05 MST 2006", "Wed Feb 25 11:06:39 PST 2015")
    do("Basic short date", "2006/01/02", "2015/02/25")

    // The hour of the reference time is 15, or 3PM. The layout can express
    // it either way, and since our value is the morning we should see it as
    // an AM time. We show both in one format string. Lower case too.
    do("AM/PM", "3PM==3pm==15h", "11AM==11am==11h")

    // When parsing, if the seconds value is followed by a decimal point
    // and some digits, that is taken as a fraction of a second even if
    // the layout string does not represent the fractional second.
    // Here we add a fractional second to our time value used above.
    t, err = time.Parse(time.UnixDate, "Wed Feb 25 11:06:39.1234 PST 2015")
    if err != nil {
        panic(err)
    }
    // It does not appear in the output if the layout string does not contain
    // a representation of the fractional second.
    do("No fraction", time.UnixDate, "Wed Feb 25 11:06:39 PST 2015")

    // Fractional seconds can be printed by adding a run of 0s or 9s after
    // a decimal point in the seconds value in the layout string.
    // If the layout digits are 0s, the fractional second is of the specified
    // width. Note that the output has a trailing zero.
    do("0s for fraction", "15:04:05.00000", "11:06:39.12340")

    // If the fraction in the layout is 9s, trailing zeros are dropped.
    do("9s for fraction", "15:04:05.99999999", "11:06:39.1234")

}

输出:

default format: 2015-02-25 11:06:39 -0800 PST
Unix format: Wed Feb 25 11:06:39 PST 2015
Same, in UTC: Wed Feb 25 19:06:39 UTC 2015

Formats:

Basic full date  "Mon Jan 2 15:04:05 MST 2006" gives "Wed Feb 25 11:06:39 PST 2015"
Basic short date "2006/01/02" gives "2015/02/25"
AM/PM            "3PM==3pm==15h" gives "11AM==11am==11h"
No fraction      "Mon Jan _2 15:04:05 MST 2006" gives "Wed Feb 25 11:06:39 PST 2015"
0s for fraction  "15:04:05.00000" gives "11:06:39.12340"
9s for fraction  "15:04:05.99999999" gives "11:06:39.1234"

示例(填充):

package main

import (
    "fmt"
    "time"
)

func main() {
    // Parse a time value from a string in the standard Unix format.
    t, err := time.Parse(time.UnixDate, "Sat Mar 7 11:06:39 PST 2015")
    if err != nil { // Always check errors even if they should not happen.
        panic(err)
    }

    // Define a helper function to make the examples' output look nice.
    do := func(name, layout, want string) {
        got := t.Format(layout)
        if want != got {
            fmt.Printf("error: for %q got %q; expected %q\n", layout, got, want)
            return
        }
        fmt.Printf("%-16s %q gives %q\n", name, layout, got)
    }

    // The predefined constant Unix uses an underscore to pad the day.
    do("Unix", time.UnixDate, "Sat Mar  7 11:06:39 PST 2015")

    // For fixed-width printing of values, such as the date, that may be one or
    // two characters (7 vs. 07), use an _ instead of a space in the layout string.
    // Here we print just the day, which is 2 in our layout string and 7 in our
    // value.
    do("No pad", "<2>", "<7>")

    // An underscore represents a space pad, if the date only has one digit.
    do("Spaces", "<_2>", "< 7>")

    // A "0" indicates zero padding for single-digit values.
    do("Zeros", "<02>", "<07>")

    // If the value is already the right width, padding is not used.
    // For instance, the second (05 in the reference time) in our value is 39,
    // so it doesn't need padding, but the minutes (04, 06) does.
    do("Suppressed pad", "04:05", "06:39")

}

输出:

Unix             "Mon Jan _2 15:04:05 MST 2006" gives "Sat Mar  7 11:06:39 PST 2015"
No pad           "<2>" gives "<7>"
Spaces           "<_2>" gives "< 7>"
Zeros            "<02>" gives "<07>"
Suppressed pad   "04:05" gives "06:39"

相关用法


注:本文由纯净天空筛选整理自golang.google.cn大神的英文原创作品 Time.Format。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。