Can you assign null value to a struct

It might make more sense to have root be a pointer instead. If you do want it to be a struct tnode object, then you can either compare its members with 0, or just the word member. Anything else would honestly be a mistake. My homepage Advice: Take only as directed - If symptoms persist, please see your debugger Linus Torvalds: "But it clearly is the only right way.

The fact that everybody else does it some other way only means that they are wrong". Replies: 3 Last Post: , AM. Check if string is null By doubty in forum C Programming. Replies: 3 Last Post: , PM. Assign null to a character array. By mahedee in forum C Programming.

Replies: 1 Last Post: , AM. Replies: 11 Last Post: , PM. Replies: 6 Last Post: , AM. A nullable value type T? For example, you can assign any of the following three values to a bool?

An underlying value type T cannot be a nullable value type itself. For more information, see Nullable reference types.

The nullable value types are available beginning with C 2. Any nullable value type is an instance of the generic System. You typically use a nullable value type when you need to represent the undefined value of an underlying value type. For example, a Boolean, or bool , variable can only be either true or false. However, in some applications a variable value can be undefined or missing. For example, a database field may contain true or false , or it may contain no value at all, that is, NULL.

You can use the bool? As a value type is implicitly convertible to the corresponding nullable value type, you can assign a value to a variable of a nullable value type as you would do that for its underlying value type. You can also assign the null value. For example:. HasValue property returns false. Beginning with C 7. You always can use the following read-only properties to examine and get a value of a nullable value type variable:.

HasValue indicates whether an instance of a nullable value type has a value of its underlying type. Value gets the value of an underlying type if HasValue is true. The following example uses the HasValue property to test whether the variable contains a value before displaying it:.

You can also compare a variable of a nullable value type with null instead of using the HasValue property, as the following example shows:. If you want to assign a value of a nullable value type to a non-nullable value type variable, you might need to specify the value to be assigned in place of null.

For example, suppose the variable U has not been defined in the current IDL session. To discard the return value from a function, assign it to! For example, suppose you wanted to find the subscripts of both the minimum and maximum values in an array using the MAX function. In the following statement:. As a result, a variable set equal to! NULL can be thought of as an empty element in an array specification.

Thinking of a null variable in this way makes it easy to add variables to an array without first checking to ensure that the array is defined. For example, you might use code like the following when building an array variable from values determined at runtime:. Here, the fact that we intialize the variable array to the value!

On the first iteration, array is equal to! NULL, and serves as an empty element that is ignored after the first variable with a defined value is added. Similarly, if we want to construct an array by adding values in another dimension, an array containing only a null value can serve as a placeholder for an entire dimension in the array:.

Here we end up creating a two-dimensional array, with each iteration adding a new array to the second dimension. Note: The value!