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For more information, see Value equality in the C language reference article about records. If you need to mutate immutable properties of a record instance, you can use a with expression to achieve nondestructive mutation. A with expression makes a new record instance that is a copy of an existing record instance, with specified properties and fields modified.
You use object initializer syntax to specify the values to be changed, as shown in the following example:. For more information, see Nondestructive mutation in the C language reference article about records. Record types have a compiler-generated ToString method that displays the names and values of public properties and fields. The ToString method returns a string of the following format:.
For reference types, the type name of the object that the property refers to is displayed instead of the property value. In the following example, the array is a reference type, so System. String[] is displayed instead of the actual array element values:. For more information, see Built-in formatting in the C language reference article about records. A record can inherit from another record. However, a record can't inherit from a class, and a class can't inherit from a record.
For two record variables to be equal, the run-time type must be equal. The types of the containing variables might be different. This is illustrated in the following code example:. In the example, all instances have the same properties and the same property values.
All public properties and fields of both derived and base types are included in the ToString output, as shown in the following example:. For more information, see Inheritance in the C language reference article about records. Init only setters provide consistent syntax to initialize members of an object.
Property initializers make it clear which value is setting which property. The downside is that those properties must be settable. Starting with C 9. Callers can use property initializer syntax to set these values in creation expressions, but those properties are readonly once construction has completed. Init only setters provide a window to change state. That window closes when the construction phase ends. The construction phase effectively ends after all initialization, including property initializers and with-expressions have completed.
You can declare init only setters in any type you write. For example, the following struct defines a weather observation structure:. Callers can use property initializer syntax to set the values, while still preserving the immutability:.
Init only setters can be useful to set base class properties from derived classes. They can also set derived properties through helpers in a base class. Positional records declare properties using init only setters. Those setters are used in with-expressions. You can declare init only setters for any class , struct , or record you define. For more information, see init C Reference. Top-level statements remove unnecessary ceremony from many applications.
Consider the canonical "Hello World! There's only one line of code that does anything. With top-level statements, you can replace all that boilerplate with the using directive and the single line that does the work:. If you wanted a one-line program, you could remove the using directive and use the fully qualified type name:.
Only one file in your application may use top-level statements. If the compiler finds top-level statements in multiple source files, it's an error. It's also an error if you combine top-level statements with a declared program entry point method, typically a Main method. In a sense, you can think that one file contains the statements that would normally be in the Main method of a Program class. One of the most common uses for this feature is creating teaching materials. I've done some scratching around and so far drawing blanks.
Lee Lee 7 7 bronze badges. Add a comment. Active Oldest Votes. Eg: versionControlServer. QueryHistory serverPath, VersionSpec.
Latest, 0, RecursionType. MaxValue, true, true ;. Edward Thomson Edward Thomson This is another way to check whether a given file is latest or not. Full , VersionSpec. Latest , GetOptions. Preview ; if status. NoActionNeeded MessegeBox. Show "Latest" ; else MessegeBox. We use Workstation. Great tutorial and help me alot. Keep doing tutorials like these. I kept what you wrote in mind as I developed the update code for my program.
Thanks again for your posts! Nice post, thanks very much. I will definitely try this out to see how it works for me. Coherent and structured tutorial with first rate examples. Thanks a million! Thanks VERY much for the tutorial! Thanks, this helps a lot! BTW, where is the WebRequest code to download the msi file? Or am I missing something??? Thanks, Peter.
Headers to get the content-length 4 create the temporary file 5 read the response stream and save the installer to the temporary file you can call ShouldStop method every 8K to check if the user canceled the action 6 in case of any errors — remove the temporary file If everything went OK, we launch the installer Greetings, mech.
Thanks in advance for your help. Greetings, mech. Anyone knows a way for displaying a progress indicator while downloading the update? Thanks a lot for this nice programm.
Please can you help me for that process. Please it is very urgent. Thanks, Manisha. Check for updates: how to download and install a new version of your C application Posted on September 11th, in c , programming 23 Comments » In one of the previous tutorials I described a simple solution that allows an application to check if a new version is available. Diego December 16, Great text and very usefull. Thiago December 21, Thanks a lot man. Jake June 26, Coherent and structured tutorial with first rate examples.
Joe T. Thanks, Peter mech February 22, Peter, Well, my fault. Headers to get the content-length 4 create the temporary file 5 read the response stream and save the installer to the temporary file you can call ShouldStop method every 8K to check if the user canceled the action 6 in case of any errors — remove the temporary file If everything went OK, we launch the installer Greetings, mech ludovic April 18, Thanks a lot, it was usefull.
TheKidd June 27, Hello Mech, thank you for such a great tutorial. RvdH September 28, Anyone knows a way for displaying a progress indicator while downloading the update?
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