Questions tagged [equals-operator]
173 questions
397
votes
14 answers
Can't operator == be applied to generic types in C#?
According to the documentation of the == operator in MSDN,
For predefined value types, the
equality operator (==) returns true if
the values of its operands are equal,
false otherwise. For reference types
other than string, == returns true…
Hosam Aly
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196
votes
7 answers
Java: Integer equals vs. ==
As of Java 1.5, you can pretty much interchange Integer with int in many situations.
However, I found a potential defect in my code that surprised me a bit.
The following code:
Integer cdiCt = ...;
Integer cdsCt = ...;
...
if (cdiCt != null && cdsCt…
Jeremy Goodell
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121
votes
3 answers
What's the meaning of "(1,) == 1," in Python?
I'm testing the tuple structure, and I found it's strange when I use the == operator like:
>>> (1,) == 1,
Out: (False,)
When I assign these two expressions to a variable, the result is true:
>>> a = (1,)
>>> b = 1,
>>> a==b
Out: True
This…
Pythoner
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101
votes
6 answers
Performance differences between equal (=) and IN with one literal value
How does SQL engines differ when we use equal sign and IN operator have same value? Does execution time changes?
1st one using equality check operator
WHERE column_value = 'All'
2nd one using IN operator and single value
WHERE column_value IN…
Somnath Muluk
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83
votes
3 answers
When is a C# value/object copied and when is its reference copied?
I keep getting the same issue over and over again where an object I want to reference is copied or where an object I want to copy is referenced. This happens when I use the = operator.
For example, if I am sending the object to another form, ie:…
Mike Webb
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76
votes
6 answers
What needs to be overridden in a struct to ensure equality operates properly?
As the title says: do I need to override the == operator? how about the .Equals() method? Anything I'm missing?
RCIX
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32
votes
4 answers
Does == check for full equality in Booleans? - Java
So I've heard that if I compare 2 strings with == then I will only get true back if they both refer to the same object/instance. That's strings. What about Booleans?
Bluefire
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28
votes
8 answers
What's wrong with defining operator == but not defining Equals() or GetHashCode()?
For the code below
public struct Person
{
public int ID;
public static bool operator ==(Person a, Person b) { return a.Equals(b); }
public static bool operator !=(Person a, Person b) { return !a.Equals(b); }
}
Why does the compiler…
user541686
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27
votes
3 answers
Equality operator overloads: Is (x!=y) == (!(x==y))?
Does the C++ standard guarantee that (x!=y) always has the same truth value as !(x==y)?
I know there are many subtleties involved here: The operators == and != may be overloaded. They may be overloaded to have different return types (which only…
Marco13
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27
votes
7 answers
Why equal operator works for Integer value until 128 number?
Why Integer == operator does not work for 128 and after Integer values? Can someone explain this situation?
This is my Java environment:
java version "1.6.0_37"
Java(TM) SE Runtime Environment (build 1.6.0_37-b06)
Java HotSpot(TM) 64-Bit Server VM…
gokhansari
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26
votes
3 answers
C# Differences between operator ==, StringBuilder.Equals, Object.Equals and Object.ReferenceEquals
I have a question about Object.Equals and Equals(object). My sample code is below:
class Program
{
static void Main(string[] args)
{
var sb1 = new StringBuilder("Food");
var sb2 = new StringBuilder("Food");
…
amitabha
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21
votes
2 answers
Does == actually work the same or different when comparing two primitives vs two Objects in Java?
When searching for explanations of how logical equals == works in Java the answers are always something along the lines of:
For primitives it returns whether the primitives have the same value (this includes comparing a primitive to its…
user7382368
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21
votes
2 answers
Argument order for '==' with Nullable
The following two C# functions differ only in swapping the left/right order of arguments to the equals operator, ==. (The type of IsInitialized is bool). Using C# 7.1 and .NET 4.7.
static void A(ISupportInitialize x)
{
if ((x as…
Glenn Slayden
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20
votes
3 answers
Difference between == operator and Equals() method in C#?
What is the difference between == and Equals() with example? I know that == is used to compare operator and Equals() method is used to compare content of string.So i tried
// first example
string s1 = "a";
string s2 =…
Jui Test
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16
votes
6 answers
Is there a reason not to use <=> (null safe equals operator) in mysql instead of =?
MySQL provides a nice operator <=> that works with comparisons that could contain a null such as null <=> null or null <=> 5 etc. giving back intuitive results as many programming languages. Whereas the normal equals operator always just returns…
fields
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