Function pow() does not work correctly when using big numbers?

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Автор HridoyHazard, история, 20 месяцев назад, По-английски

i came to know this error recently while using pow function for a large data such as

pow(8376260,70)

it giving 0 as output which is wrong. i tried using long and unsigned but it giving the same output. is there any way to use large data in pow function??

-4

HridoyHazard
20 месяцев назад
7

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Abito

20 месяцев назад, # |

← Rev. 2 →

Yeah this function is kinda weird so it does problems. Create your own pow function so it doesn't cause problems. Also the numbers you are using are very large so it will overflow

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chromate00

20 месяцев назад, # ^ |

The function is fine, it even reports errors when it happens. You can check such errors with the errno macro.

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Abito

20 месяцев назад, # ^ |

Thanks. I never lnew that. But isn't implementing the function yourself better? Especially when you have to do it for large numbers where you have to use mod

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chromate00

20 месяцев назад, # ^ |

yep, in this case that would probably be the only option.

(unless you're using python, of course)

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Imdie

20 месяцев назад, # |

the pow function returns a "double" type.

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Vahagn_Grigoryan

20 месяцев назад, # |

You'd better use binary pow.

const long long MOD = 1e9 + 7;
long long binpow(long long n, long long p){
	long long res = 1;
	while(p) {
		if(p & 1) {
			res *= n;
			res %= MOD;
		}
		p >>= 1;
		n *= n;
		n %= MOD;
	}
	return res;
}

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