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--- title: Bicep null-forgiving operator description: Describes Bicep null-forgiving operator. ms.topic: reference ms.custom: devx-track-bicep ms.date: 10/30/2025 --- # Bicep null-forgiving operator The unary postfix `!` operator is the null-forgiving, or null-suppression, operator. It's used to suppress all nullable warnings for the preceding expression. The null-forgiving operator has no effect at run time. It only affects the compiler's static flow analysis by changing the null state of the expression. At run time, expression `x!` evaluates to the result of the underlying expression `x`. ## Null-forgiving `expression!` The null-forgiving operator ensures that a value isn't null, changing the assigned type of the value from `null | <type>` to `<type>`. The following example fails the design time validation: ```bicep param inputString string output outString string = first(skip(split(inputString, '/'), 1)) ``` The warning message is: ```error Expected a value of type "string" but the provided value is of type "null | string". ``` To solve the problem, use the null-forgiving operator: ```bicep param inputString string output outString string = first(skip(split(inputString, '/'), 1))! ``` ## Next steps - To run the examples, use Azure CLI or Azure PowerShell to [deploy a Bicep file](./quickstart-create-bicep-use-visual-studio-code.md#deploy-the-bicep-file). - To create a Bicep file, see [Quickstart: Create Bicep files with Visual Studio Code](./quickstart-create-bicep-use-visual-studio-code.md). - For information about how to resolve Bicep type errors, see [Any function for Bicep](./bicep-functions-any.md).