使用PowerShell将String转换为Date

Question

我的日期为字符串，格式如下：

July 27th, 2016
December 3rd, 2014
August 1st, 1998
March 2nd, 1979

如何使用PowerShell将日期转换为以下内容

2016-07-27
2014-12-03
1998-08-01
1979-03-02

Answer 1

我会选择使用某些正则表达式ParseExact()来删除所有的，rd＆＃39; s。 您只需在ToString()

中使用正确的格式

编辑根据@JosefZ建议更新代码。

foreach ($date in @(
    'July 27th, 2016'
    'December 3rd, 2014'
    'August 1st, 1998'
    'March 2nd, 1979'
)) {
    $clean = $date -replace '(st|nd|rd|th),'
    $dateObject = [datetime]::ParseExact($clean, 'MMMM d yyyy', [System.Globalization.CultureInfo]::InvariantCulture)
    # Apparently, this works too ...    
    $dateObject = [datetime]$clean  
    $dateObject.ToString('yyyy-MM-dd')
}

Answer 2

我没有足够的代表来评论BartekB的解决方案，所以这里只是他的答案的一个小正则表达式替代。

foreach ($oldformat in @(
    'July 27th, 2016'
    'December 3rd, 2014'
    'August 1st, 1998'
    'March 2nd, 1979')
    ) 
{
$newformat = [datetime][regex]::replace($oldformat,' *..,',"") | Get-Date -Format "yyyy-MM-dd"
Write-Host $newformat
}

Answer 3

除了@ Andrii-Matus，@ BagekB所示的方法之外，以下是另一种实现同样目的的方法。

$date_str = @(
    'July 27th, 2016'
    'December 3rd, 2014'
    'August 1st, 1998'
    'March 2nd, 1979'
)

foreach ($date in $date_str){
    $newformat = $date -replace '(st|nd|rd|th),'
    get-date $newformat -UFormat "%Y-%m-%d"
}