Hash collision Probability

This is a discussion on Hash collision Probability within the General Discussions forums, part of the Community Boards category; Hi all I would like to know from where this equation came: Hash collision Probability = 2^-n = 1/2^n Please ...

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    Hash collision Probability

    Hi all

    I would like to know from where this equation came:
    Hash collision Probability = 2^-n = 1/2^n
    Please help me!
    Last edited by Salem; 08-02-2012 at 07:03 AM. Reason: font abuse

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    C++ Witch laserlight's Avatar
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    This thread was split from trouble with hash function implementing.

    Quote Originally Posted by Mustafa_Ayoob
    I would like to know from where this equation came:
    Hash collision Probability = 2^-n = 1/2^n
    You probably should provide some context, unless you are really talking about why the equation is so, in which case it is a matter of mathematics.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    no am sorry , but i want to know from where the above equation came? it's used to calculate the collision if happend in hash function, am not talking about programming in c++..
    Last edited by Salem; 08-02-2012 at 07:03 AM. Reason: more font abuse

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    C++ Witch laserlight's Avatar
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    Quote Originally Posted by Mustafa_Ayoob
    i want to know from where the above equation came? it's used to calculate the collision if happend in hash function
    You should be the one telling us that: where did you encounter it, and what is the hash function?
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    ok i find the solution
    it is basic propability calculation cames form Statistic.

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