String.IsNullOrEmpty(String) String.IsNullOrEmpty(String) String.IsNullOrEmpty(String) String.IsNullOrEmpty(String) Method

Definition

지정된 문자열이 null이거나 Empty 문자열인지를 나타냅니다. Indicates whether the specified string is null or an Empty string.

public:
 static bool IsNullOrEmpty(System::String ^ value);
public static bool IsNullOrEmpty (string value);
static member IsNullOrEmpty : string -> bool
Public Shared Function IsNullOrEmpty (value As String) As Boolean

매개 변수

value
String String String String

테스트할 문자열입니다. The string to test.

Returns

true 매개 변수가 value이거나 빈 문자열("")이면 null이고, 그러지 않으면 false입니다. true if the value parameter is null or an empty string (""); otherwise, false.

Examples

다음 예제에서는 세 개의 문자열을 검사 하 고 각 문자열 값, 빈 문자열이 면 중인지 여부를 결정 null합니다.The following example examines three strings and determines whether each string has a value, is an empty string, or is null.

using namespace System;
String^ Test( String^ s )
{
   if (String::IsNullOrEmpty(s))
      return "is null or empty";
   else
      return String::Format( "(\"{0}\") is neither null nor empty", s );
}

int main()
{
   String^ s1 = "abcd";
   String^ s2 = "";
   String^ s3 = nullptr;
   Console::WriteLine( "String s1 {0}.", Test( s1 ) );
   Console::WriteLine( "String s2 {0}.", Test( s2 ) );
   Console::WriteLine( "String s3 {0}.", Test( s3 ) );
}
// The example displays the following output:
//       String s1 ("abcd") is neither null nor empty.
//       String s2 is null or empty.
//       String s3 is null or empty.
using System;

class Sample 
{
    public static void Main() 
    {
    string s1 = "abcd";
    string s2 = "";
    string s3 = null;

    Console.WriteLine("String s1 {0}.", Test(s1));
    Console.WriteLine("String s2 {0}.", Test(s2));
    Console.WriteLine("String s3 {0}.", Test(s3));
    }

    public static String Test(string s)
    {
    if (String.IsNullOrEmpty(s)) 
        return "is null or empty";
    else
        return String.Format("(\"{0}\") is neither null nor empty", s);
    }
}
// The example displays the following output:
//       String s1 ("abcd") is neither null nor empty.
//       String s2 is null or empty.
//       String s3 is null or empty.
Class Sample
   Public Shared Sub Main()
      Dim s1 As String = "abcd"
      Dim s2 As String = ""
      Dim s3 As String = Nothing
      
      Console.WriteLine("String s1 {0}.", Test(s1))
      Console.WriteLine("String s2 {0}.", Test(s2))
      Console.WriteLine("String s3 {0}.", Test(s3))
   End Sub
   
   Public Shared Function Test(s As String) As String
      If String.IsNullOrEmpty(s) Then
         Return "is null or empty"
      Else
         Return String.Format("(""{0}"") is neither null nor empty", s)
      End If
   End Function 
End Class  
' The example displays the following output:
'       String s1 ("abcd") is neither null nor empty.
'       String s2 is null or empty.
'       String s3 is null or empty.

Remarks

IsNullOrEmpty 동시에 테스트할 수 있는 편리한 메서드입니다 여부를 String 됩니다 null 여부나 해당 값이 Empty합니다.IsNullOrEmpty is a convenience method that enables you to simultaneously test whether a String is null or its value is Empty. 다음 코드는 동일 합니다.It is equivalent to the following code:

result = s == nullptr || s == String::Empty;
result = s == null || s == String.Empty;
result = s Is Nothing OrElse s = String.Empty

사용할 수는 IsNullOrWhiteSpace 문자열 인지 여부를 테스트 하는 방법 null, 해당 값은 String.Empty, 공백 문자 으로만 구성 또는 합니다.You can use the IsNullOrWhiteSpace method to test whether a string is null, its value is String.Empty, or it consists only of white-space characters.

Null 문자열 이란?What is a null string?

문자열이 null 아니면 값이 명시적으로 할당 된 값 (c + + 및 Visual Basic) 할당 되지 않은 경우 null합니다.A string is null if it has not been assigned a value (in C++ and Visual Basic) or if has explicitly been assigned a value of null. 하지만 합니다 복합 서식 지정 기능 해당 멤버를 throw 하는 경우 하나를 호출 하는 동안, 다음 예제와 같이 null 문자열을 정상적으로 처리할 수는 NullReferenceException.Although the composite formatting feature can gracefully handle a null string, as the following example shows, attempting to call one if its members throws a NullReferenceException.

using namespace System;

void main()
{
   String^ s;
  
   Console::WriteLine("The value of the string is '{0}'", s);

   try {
      Console::WriteLine("String length is {0}", s->Length);
   }
   catch (NullReferenceException^ e) {
      Console::WriteLine(e->Message);
   }   
}
// The example displays the following output:
//     The value of the string is ''
//     Object reference not set to an instance of an object.
using System;

public class Example
{
   public static void Main()
   {
      String s = null;
      
      Console.WriteLine("The value of the string is '{0}'", s);

      try {
         Console.WriteLine("String length is {0}", s.Length);
      }
      catch (NullReferenceException e) {
         Console.WriteLine(e.Message);
      }
   }
}
// The example displays the following output:
//     The value of the string is ''
//     Object reference not set to an instance of an object.
Module Example
   Public Sub Main()
      Dim s As String

      Console.WriteLine("The value of the string is '{0}'", s)

      Try 
         Console.WriteLine("String length is {0}", s.Length)
      Catch e As NullReferenceException
         Console.WriteLine(e.Message)
      End Try   
   End Sub
End Module
' The example displays the following output:
'     The value of the string is ''
'     Object reference not set to an instance of an object.

빈 문자열 이란?What is an empty string?

문자열은 빈 문자열을 명시적으로 할당 하는 경우 빈 ("") 또는 String.Empty합니다.A string is empty if it is explicitly assigned an empty string ("") or String.Empty. 빈 문자열에는 Length 0입니다.An empty string has a Length of 0. 다음 예제에서는 빈 문자열을 만들고 해당 값 및 해당 길이 표시 합니다.The following example creates an empty string and displays its value and its length.

String^ s = "";
Console::WriteLine("The length of '{0}' is {1}.", s, s->Length);
// The example displays the following output:
//       The length of '' is 0.      
String s = "";
Console.WriteLine("The length of '{0}' is {1}.", s, s.Length);
// The example displays the following output:
//       The length of '' is 0.      
Dim s As String = ""
Console.WriteLine("The length of '{0}' is {1}.", s, s.Length)
' The example displays the following output:
'        The length of '' is 0.      

Applies to

See Also