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# using big integer values in cpp

how can we use big integer values in cpp? is there any library ? i have already tried long long unsigned int and the requirement of my program is even more than this.

12 Answers

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Saurabh Tiwari The easy way would be to use a string and simply apply addition and subtraction like you learned in school.
You know add 2 digits and keep track of any carries.
The more efficient, longer and less trivial solution would be to an array and store each number in base 2^64-1.
I recommend that you download the library and read through its source code and learn from it, which does exactly that.

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Default
Sahil Bhakat
thanks guys
but i have to use modulo (%) operator and double doesnt allow it

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I know it isn't an integer, but... how about long double?
This is 128-bits (2^128 MAX), opposed to unsigned long long int's (2^64 MAX).

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Dennis can you explain how to do that.
Thnxđ

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How big does the number have to be?

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Here is a big integer library: https://mattmccutchen.net/bigint/
It's pretty old though, but still good.

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Saurabh Tiwari No it's not, you could implement a simple big int class yourself though. :)
Sadly using long double isn't accurate anymore after 2^64-1.

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Yeah Default is right you can use long double it has a range from -1.7Ă10^(4932) upto 1.7Ă10^(4932).

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Default 10^200

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Or you you have to put variable somewhere where double will give give you a error

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Do you have to use it in a comparison statement or something? ?

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Dennis but it is not supported in SL's compiler