Matching '' operator is required for '

Question

1.00/5 (1 vote)

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I am using the following code snippets for overloading < operator

C#

Class example
{

static bool operator < (example a ,example b)
{
 /* code goes here*/
}
}

when i try to compile it,I get a error saying that
the operator < requires a matching operator > also to be defined.

How to over come this error

Posted 21-Mar-12 2:04am

bsb25

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2 solutions

Solution 2

have a look at the following url for knowing the reason :
http://www.vijaymukhi.com/documents/books/csbasics/chap12.htm[^]
http://msdn.microsoft.com/en-us/library/edbzxf5f%28v=vs.90%29.aspx[^]

Posted 21-Mar-12 2:38am

member60

Updated 21-Mar-12 2:40am

v2

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OriginalGriff · Accepted Answer · 2012-03-21T02:07:00

Solution 1

What it means is that if you declare a "less than" operator, you must also declare a "greater than" operator. Add this at a minimum:

C#

static bool operator > (example a ,example b)
{
 return !(b < a);
}

Posted 21-Mar-12 2:07am

OriginalGriff

Comments

bsb25 21-Mar-12 8:25am

Thanks..never knew that solution will be this easy...

Btw Can any one explain me why does C# wants both the operators to be declared??

OriginalGriff 21-Mar-12 8:40am

AFAIK it isn't specified anywhere, but it is probably to do with optimisations: If both are defined, then the compiler is free to generate code using either as seems more appropriate at the time.

OriginalGriff 21-Mar-12 8:40am

Forgot: the requirement is specifically stated here: http://msdn.microsoft.com/en-us/library/8edha89s(v=vs.71).aspx

Sergey Alexandrovich Kryukov 21-Mar-12 19:23pm

Exactly. But the speculations on optimization is valid, I think, even though some stupid implementation could screw it up: imagine someone implemented < much slower than >, there is no a way a compiler could know it in advance...

Again, a 5 for the answer.
--SA