String.PadLeft 方法

定义

返回一个指定长度的新字符串,其中在当前字符串的开头填充空格或指定的 Unicode 字符。Returns a new string of a specified length in which the beginning of the current string is padded with spaces or with a specified Unicode character.

重载

PadLeft(Int32, Char)

返回一个新字符串,该字符串通过在此实例中的字符左侧填充指定的 Unicode 字符来达到指定的总长度,从而使这些字符右对齐。Returns a new string that right-aligns the characters in this instance by padding them on the left with a specified Unicode character, for a specified total length.

PadLeft(Int32)

返回一个新字符串,该字符串通过在此实例中的字符左侧填充空格来达到指定的总长度,从而实现右对齐。Returns a new string that right-aligns the characters in this instance by padding them with spaces on the left, for a specified total length.

PadLeft(Int32, Char)

返回一个新字符串,该字符串通过在此实例中的字符左侧填充指定的 Unicode 字符来达到指定的总长度,从而使这些字符右对齐。Returns a new string that right-aligns the characters in this instance by padding them on the left with a specified Unicode character, for a specified total length.

public:
 System::String ^ PadLeft(int totalWidth, char paddingChar);
public string PadLeft (int totalWidth, char paddingChar);
member this.PadLeft : int * char -> string
Public Function PadLeft (totalWidth As Integer, paddingChar As Char) As String

参数

totalWidth
Int32

结果字符串中的字符数,等于原始字符数加上任何其他填充字符。The number of characters in the resulting string, equal to the number of original characters plus any additional padding characters.

paddingChar
Char

Unicode 填充字符。A Unicode padding character.

返回

与此实例等效的一个新字符串,但该字符串为右对齐,因此,在左侧填充所需任意数量的 paddingChar 字符,使长度达到 totalWidthA new string that is equivalent to this instance, but right-aligned and padded on the left with as many paddingChar characters as needed to create a length of totalWidth. 但是,如果 totalWidth 小于此实例的长度,则此方法返回对现有实例的引用。However, if totalWidth is less than the length of this instance, the method returns a reference to the existing instance. 如果 totalWidth 等于此实例的长度,则此方法返回与此实例相同的新字符串。If totalWidth is equal to the length of this instance, the method returns a new string that is identical to this instance.

异常

totalWidth 小于零。totalWidth is less than zero.

示例

下面的示例演示 PadLeft 方法。The following example demonstrates the PadLeft method.

using namespace System;

void main()
{
   String^ str = "forty-two";
   Console::WriteLine( str->PadLeft( 15, L'.' ) ); 
   Console::WriteLine( str->PadLeft( 2, L'.' ) ); 
}
// The example displays the following output:
//       ......forty-two
//       forty-two
using System;

class Sample
{
   public static void Main()
   { 
   string str = "forty-two";
   char pad = '.';

   Console.WriteLine(str.PadLeft(15, pad));  
   Console.WriteLine(str.PadLeft(2, pad));  
   }
}
// The example displays the following output:
//       ......forty-two
//       forty-two
Public Class Example
   Public Shared Sub Main()
      Dim str As String
      Dim pad As Char
      str = "forty-two"
      pad = "."c
      Console.WriteLine(str.PadLeft(15, pad)) 
      Console.WriteLine(str.PadLeft(2,  pad))
    End Sub
End Class
' The example displays the following output:
'       ......forty-two
'       forty-two

注解

PadLeft(Int32, Char) 方法用于填充返回的字符串的开头。The PadLeft(Int32, Char) method pads the beginning of the returned string. 这意味着,当与从右到左的语言结合使用时,它将填充字符串的右侧部分。This means that, when used with right-to-left languages, it pads the right portion of the string.

备注

如果 PadLeft 方法用空白字符填充当前实例,则此方法不会修改当前实例的值。If the PadLeft method pads the current instance with white-space characters, this method does not modify the value of the current instance. 相反,它会返回一个新字符串,该字符串使用前导 paddingChar 字符进行填充,以便其总长度为 totalWidth 个字符。Instead, it returns a new string that is padded with leading paddingChar characters so that its total length is totalWidth characters.

另请参阅

PadLeft(Int32)

返回一个新字符串,该字符串通过在此实例中的字符左侧填充空格来达到指定的总长度,从而实现右对齐。Returns a new string that right-aligns the characters in this instance by padding them with spaces on the left, for a specified total length.

public:
 System::String ^ PadLeft(int totalWidth);
public string PadLeft (int totalWidth);
member this.PadLeft : int -> string
Public Function PadLeft (totalWidth As Integer) As String

参数

totalWidth
Int32

结果字符串中的字符数,等于原始字符数加上任何其他填充字符。The number of characters in the resulting string, equal to the number of original characters plus any additional padding characters.

返回

与此实例等效的一个新字符串,但该字符串为右对齐,因此,在左侧填充所需任意数量的空格,使长度达到 totalWidthA new string that is equivalent to this instance, but right-aligned and padded on the left with as many spaces as needed to create a length of totalWidth. 但是,如果 totalWidth 小于此实例的长度,则此方法返回对现有实例的引用。However, if totalWidth is less than the length of this instance, the method returns a reference to the existing instance. 如果 totalWidth 等于此实例的长度,则此方法返回与此实例相同的新字符串。If totalWidth is equal to the length of this instance, the method returns a new string that is identical to this instance.

异常

totalWidth 小于零。totalWidth is less than zero.

示例

下面的示例演示 PadLeft 方法。The following example demonstrates the PadLeft method.

String^ str = "BBQ and Slaw";
Console::WriteLine( str->PadLeft( 15 ) ); // Displays "   BBQ and Slaw".
Console::WriteLine( str->PadLeft( 5 ) );  // Displays "BBQ and Slaw".
string str = "BBQ and Slaw";
Console.WriteLine(str.PadLeft(15));  // Displays "   BBQ and Slaw".
Console.WriteLine(str.PadLeft(5));   // Displays "BBQ and Slaw".
Dim str As String
str = "BBQ and Slaw"
Console.WriteLine(str.PadLeft(15)) ' Displays "   BBQ and Slaw".
Console.WriteLine(str.PadLeft(5))  ' Displays "BBQ and Slaw".

注解

Unicode 空格定义为十六进制0x0020。A Unicode space is defined as hexadecimal 0x0020.

PadLeft(Int32) 方法用于填充返回的字符串的开头。The PadLeft(Int32) method pads the beginning of the returned string. 这意味着,当与从右到左的语言结合使用时,它将填充字符串的右侧部分。This means that, when used with right-to-left languages, it pads the right portion of the string.

备注

如果 PadLeft 方法用空白字符填充当前实例,则此方法不会修改当前实例的值。If the PadLeft method pads the current instance with white-space characters, this method does not modify the value of the current instance. 相反,它会返回一个新字符串,该字符串由前导空格填充,使其总长度为 totalWidth 个字符。Instead, it returns a new string that is padded with leading white space so that its total length is totalWidth characters.

另请参阅

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