Why is my Go `time.Parse` function returning an unexpected time value?

Understanding time.Parse Behavior in Go

When attempting to convert strings to time.Time values in Go using the time.Parse method, setting the correct format string is crucial to obtain the expected result.

Consider the following code snippet:

package main

import (
    "fmt"
    "time"
)

func main() {
    const longForm = "2013-05-13T18:41:34.848Z"
    //even this is not working
    //const longForm = "2013-05-13 18:41:34.848 -0700 PDT"
    t, _ := time.Parse(longForm, "2013-05-13 18:41:34.848 -0700 PDT")
    fmt.Println(t)
}

The code attempts to parse a string in the format "2013-05-13 18:41:34.848 -0700 PDT" using the longForm format string. However, the output is unexpected: "0001-01-01 00:00:00 0000 UTC".

To understand this behavior, it's important to note that the default reference time for the time.Parse method is "Mon Jan 2 15:04:05 MST 2006", which represents Unix time 1136239445. This means that the format string must represent the reference time accordingly.

In the given code, the longForm format string incorrectly represents the reference time as "2006-01-02 15:04:05 -0700". This mismatch in the reference time format leads to the unexpected output.

To resolve this issue, the longForm format string should be modified to match the reference time:

package main

import (
        "fmt"
        "log"
        "time"
)

func main() {
        const longForm = "2006-01-02 15:04:05 -0700"
        t, err := time.Parse(longForm, "2013-05-13 18:41:34.848 -0700")
        if err != nil {
                log.Fatal(err)
        }
        fmt.Println(t)
}

With the correct longForm format string, the time.Parse method now accurately converts the string to a time.Time value: "2013-05-13 01:41:34.848 0000 UTC".

The above is the detailed content of Why is my Go `time.Parse` function returning an unexpected time value?. For more information, please follow other related articles on the PHP Chinese website!