Can anyone tell me how to get large fatorials in c++...in c++ i am getting the ouput upto maximum of 20!
any please help how to solve this issue.
any please help how to solve this issue.
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The problem is that factorials quickly get too large to be represented in the standard C integer types.- unsigned 8-bits can hold at most 5!
- unsigned 16-bits can hold at most 8!
- unsigned 32-bits can hold at most 12!
- unsigned 64-bits can hold at most 20!
- Excel formula for bits required to hold n!: ROUNDUP(LOG(FAC T(n),2),0)
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@dinbock:
i haven't understood the last statement "ROUNDUP(LOG(FA CT(n),2),0)"
could u please explain it brieflyComment
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You can express a large number as a string or as an array.
In C++ you would design a class to contain the array with member functions that work with the array to let you do math on the elements.Comment
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@saiavinashiitr -that last line is an Excel formula. For example, to find out how many bits it takes to hold the value of 100!, type this into an Excel spreadsheet cell: =ROUNDUP(LOG(FA CT(100),2),0)- FACT(100) returns the value of 100!, call it a.
- LOG(a,2) returns the base 2 logarithm of 100!., call it b.
- ROUNDUP(b,0) rounds the logarithm up to the next integer.
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