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What is an empty string equal to?
An empty string is a String object with an assigned value, but its length is equal to zero. A null string has no value at all.
Why is null == 0 false?
Comparisons convert null to a number, treating it as 0 . That’s why (3) null >= 0 is true and (1) null > 0 is false. On the other hand, the equality check == for undefined and null is defined such that, without any conversions, they equal each other and don’t equal anything else. That’s why (2) null == 0 is false.
What is in an empty string?
A String object that contains no characters is still an object. Such an object is called an empty string. It is similar to having a blank sheet of paper (different from having no paper at all). Overlooking this difference is one of the classic confusions of computer programming.
Is 0 == null in Java?
8 Answers. null means that a variable contains a reference to a space in memory that does not contain an object. 0 is a numeric data type with a value of 0. Nothing doesn’t really exist, however I think you may be viewing this as an empty String “” which is simply a String data type that does not contain a value.
Is 0 null JS?
Comparisons convert null to a number, treating it as 0 . That’s why (3) null >= 0 is true and (1) null > 0 is false . On the other hand, the equality check == for undefined and null is defined such that, without any conversions, they equal each other and don’t equal anything else.
What happens when an empty string is converted to a date?
As noted in the comments the empty string gets converted to 0 in any numeric type and to 1900-01-01 00:00:00.000 when converted to a date. EDIT: I think your real problem is that your design is so that you have to join on fields of a different data type.
Why does PHP consider 0 to be equal to a string?
So as we said, PHP has a problem (not a problem but weird behavior) only when the number / string 0 (or “0”) is present echo (23 == “24”); // false. values aren’t equal (unlike last example). The type is less relevant with the == operator as we can see.
When is null reference equivalent to a string literal?
When doing a string comparison, a null reference is equivalent to the string literal “”. If you are interested in further details, I have written an in-depth comparison of vbNullString, String.Empty, “” and Nothing in VB.NET here:
Can a string be converted to a string?
When converted to a particular type, it is the equivalent of the default value of that type. So, when you test against String.Empty, Nothing is converted to a string, which has a length 0.