How we can able to create User defined long long int for large numbers in CPP.??

For large number in c++ which go beyond the long long u have to manipulate as string and then for algebraic operation u can write basic function for addition , subtractionâ€¦and so on.

depends on how large the number is, use uint64_t, it can handle numbers upto 2^64.

To create long long int you do this:

```
long long var; //var can hold up to 2^63-1 ("long long" or "long long int" is the same thing)
```

To go beyond this limit you can use libraries like boost, or make your own.

If you use python or java, you can do it without any external libraries.

shouldnâ€™t it be unsigned long long to hold upto 2^64

Correct, Iâ€™ve edited it.

How we can able to create User-defined long long int for large numbers in CPP.??

well, you can use this big-int class this has pretty much all the important algebraic functions you need with a number.

[https://github.com/amit-nits/justforsharing/blob/master/classbigint.cpp](http://class big int)

This is literally user defined big-int datatype.