Hi,@Shervan360 . Welcome Microsoft Q&A.
In C#, string? and string are different in terms of nullable reference types.
This represents a nullable string, which is a string that can have a value or be null.
The ? after the type indicates that the variable can be assigned a value of the specified type or be assigned null.
In C# 8.0 and later versions, nullable reference types are enabled by default, so string? is treated as a nullable string. It means the compiler will perform static analysis to help prevent null reference exceptions.
This represents a regular non-nullable string, which cannot be assigned a value of null.
Without the ?, the string variable is treated as a regular string, and it must always have a valid string value.
The behavior of nullable reference types might vary depending on the version of C# and the compiler settings. Starting from C# 8.0 (Nullable reference types in C#), nullable reference types are enabled by default, but you can also control their behavior with the use of nullable annotations and nullable context options.
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