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IsNullOrEmpty is used with strings to check if a string is null or empty. Is there an equivalent with an object to see if any object is null or not? I assume we can do
obj1 != null
but not sure if there is any other way...
997
To test if an object is null: instead of using (obj1 == null) you can use bool bIsNull = object. Equals(obj1, null);
null (C# Reference)The null keyword is a literal that represents a null reference, one that does not refer to any object. null is the default value of reference-type variables.
The main difference between IsNullOrEmpty and IsNullOrWhiteSpace in C# is that IsNullOrEmpty checks if there's at least one character, while IsNullOrWhiteSpace checks every character until it finds a non-white-space character.
I found that DataGridViewTextBox values and some JSON objects don't equal Null but instead are "{}" values. Comparing them to Null doesn't work but using these do the trick:
if (cell.Value is System.DBNull)
if (cell.Value == System.DBNull.Value)
A good excerpt I found concerning the difference between Null and DBNull:
Do not confuse the notion of null in an object-oriented programming language with a DBNull object. In an object-oriented programming language, null means the absence of a reference to an object. DBNull represents an uninitialized variant or nonexistent database column.
You can learn more about the DBNull class here.
166
a null string is null, an empty string is ""
isNullOrEmpty requires an intimate understanding about the implementation of a string. If you want one, you can write one yourself for your object, but you have to make your own definition for whether your object is "empty" or not.
ask yourself: What does it mean for an object to be empty?
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