Contract.Assert Method (Boolean, String)

Checks for a condition; if the condition is false, follows the escalation policy set by the analyzer and displays the specified message.

Namespace:  System.Diagnostics.Contracts
Assembly:  mscorlib (in mscorlib.dll)


<ConditionalAttribute("CONTRACTS_FULL")> _
<ConditionalAttribute("DEBUG")> _
Public Shared Sub Assert ( _
    condition As Boolean, _
    userMessage As String _
public static void Assert(
    bool condition,
    string userMessage


  • userMessage
    Type: System.String
    A message to display if the condition is not met.


The default escalation policy is to notify the attached debugger about a contract failure or to display an Assert dialog box if a debugger is not attached. Optionally, the analyzer can be instructed to throw an exception. The userMessage parameter is passed to the debugger output. If userMessage is not a constant string literal, tools may not be able to read it.

Version Information


Supported in: 5, 4


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