Privacy policy. An attempt was made to modify a value type that is produced as the result of an intermediate expression but is not stored in a variable. This error can occur when you attempt to directly modify a struct in a generic collection, as shown in the following example:. To modify the struct, first assign it to a local variable, modify the variable, then assign the variable back to the item in the collection.
This error occurs because value types are copied on assignment. When you retrieve a value type from a property or indexer, you are getting a copy of the object, not a reference to the object itself.
The copy that is returned is not stored by the property or indexer because they are actually methods, not storage locations variables. You must store the copy into a variable that you declare before you can modify it. The error does not occur with reference types because a property or indexer in that case returns a reference to an existing object, which is a storage location.
If you are defining the class or struct, you can resolve this error by modifying your property declaration to provide access to the members of a struct. If you are writing client code, you can resolve the error by creating your own instance of the struct, modifying its fields, and then assigning the entire struct back to the property.
As a third alternative, you can change your struct to a class. Privacy policy. Invalid option 'option' for LangVersion. This error occurs if you used the LangVersion command line switch or project setting but didn't specify a valid language option. To resolve this error, check the command line syntax or project setting and change it to one of the listed options. The valid values for the language versions depend on the.
NET version you are using. See the language version rules for more information on which language version is available with which version of. If you are receiving this error while attempting to use a newer language version, either downgrade to a lower language version or update your. Skip to main content. This browser is no longer supported.
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