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Boolean.TryParse Method

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Definition

Namespace:
System
Assembly:
System.Runtime.dll
Assembly:
netstandard.dll
Assembly:
mscorlib.dll

Overloads

TryParse(ReadOnlySpan<Char>, Boolean)

Tries to convert the specified span representation of a logical value to its Boolean equivalent.
TryParse(String, Boolean)

Tries to convert the specified string representation of a logical value to its Boolean equivalent.

TryParse(ReadOnlySpan<Char>, Boolean)

Source:
Boolean.cs
Source:
Boolean.cs
Source:
Boolean.cs

Tries to convert the specified span representation of a logical value to its Boolean equivalent.

public:
 static bool TryParse(ReadOnlySpan<char> value, [Runtime::InteropServices::Out] bool % result);
public static bool TryParse (ReadOnlySpan<char> value, out bool result);
static member TryParse : ReadOnlySpan<char> * bool -> bool
Public Shared Function TryParse (value As ReadOnlySpan(Of Char), ByRef result As Boolean) As Boolean

Parameters

value
ReadOnlySpan<Char>

A span containing the characters representing the value to convert.

result
Boolean

When this method returns, if the conversion succeeded, contains true if value is equal to TrueString or false if value is equal to FalseString. If the conversion failed, contains false. The conversion fails if value is null or is not equal to the value of either the TrueString or FalseString field.

Returns

Boolean

true if value was converted successfully; otherwise, false.

Applies to

TryParse(String, Boolean)

Source:
Boolean.cs
Source:
Boolean.cs
Source:
Boolean.cs

Tries to convert the specified string representation of a logical value to its Boolean equivalent.

public:
 static bool TryParse(System::String ^ value, [Runtime::InteropServices::Out] bool % result);
public static bool TryParse (string value, out bool result);
public static bool TryParse (string? value, out bool result);
static member TryParse : string * bool -> bool
Public Shared Function TryParse (value As String, ByRef result As Boolean) As Boolean

Parameters

value
String

A string containing the value to convert.

result
Boolean

When this method returns, if the conversion succeeded, contains true if value is equal to TrueString or false if value is equal to FalseString. If the conversion failed, contains false. The conversion fails if value is null or is not equal to the value of either the TrueString or FalseString field.

Returns

Boolean

true if value was converted successfully; otherwise, false.

Examples

The following example calls the TryParse method to parse an array of strings. Note that the parse operation succeeds only if the string to be parsed is "True" (the value of the TrueString field) or "False" (the value of the FalseString field) in a case-insensitive comparison.

using System;

public class Example
{
   public static void Main()
   {
      string[] values = { null, String.Empty, "True", "False",
                          "true", "false", "    true    ", "0",
                          "1", "-1", "string" };
      foreach (var value in values) {
         bool flag;
         if (Boolean.TryParse(value, out flag))
            Console.WriteLine("'{0}' --> {1}", value, flag);
         else
            Console.WriteLine("Unable to parse '{0}'.",
                              value == null ? "<null>" : value);
      }
   }
}
// The example displays the following output:
//       Unable to parse '<null>'.
//       Unable to parse ''.
//       'True' --> True
//       'False' --> False
//       'true' --> True
//       'false' --> False
//       '    true    ' --> True
//       Unable to parse '0'.
//       Unable to parse '1'.
//       Unable to parse '-1'.
//       Unable to parse 'string'.

open System

let values = 
    [ null; String.Empty; "True"; "False"
      "true"; "false"; "    true    "; "0"
      "1"; "-1"; "string" ]
for value in values do
    match Boolean.TryParse value with
    | true, flag ->
        printfn $"'{value}' --> {flag}"
    | false, _ ->
        printfn $"""Unable to parse '%s{if value = null then "<null>" else value}'."""

// The example displays the following output:
//       Unable to parse '<null>'.
//       Unable to parse ''.
//       'True' --> True
//       'False' --> False
//       'true' --> True
//       'false' --> False
//       '    true    ' --> True
//       Unable to parse '0'.
//       Unable to parse '1'.
//       Unable to parse '-1'.
//       Unable to parse 'string'.

Module Example
   Public Sub Main()
      Dim values() As String = { Nothing, String.Empty, "True", "False", 
                                 "true", "false", "    true    ", "0", 
                                 "1", "-1", "string" }
      For Each value In values
         Dim flag As Boolean
         
         If Boolean.TryParse(value, flag) Then
            Console.WriteLine("'{0}' --> {1}", value, flag)
         Else
            Console.WriteLine("Unable to parse '{0}'.", 
                              If(value Is Nothing, "<null>", value))
         End If         
      Next                                     
   End Sub
End Module
' The example displays the following output:
'       Unable to parse '<null>'.
'       Unable to parse ''.
'       'True' --> True
'       'False' --> False
'       'true' --> True
'       'false' --> False
'       '    true    ' --> True
'       Unable to parse '0'.
'       Unable to parse '1'.
'       Unable to parse '-1'.
'       Unable to parse 'string'.

Remarks

The TryParse method is like the Parse method, except the TryParse method does not throw an exception if the conversion fails.

The value parameter can be preceded or followed by white space. The comparison is ordinal and case-insensitive.

See also

Applies to