英文:
Why pow() function in python and pow() function in dart produces different result for same input?
问题
我想在Dart语言中评估pow(17,18)，但它产生了6665467901046659617。在Python语言中，相同的表达式pow(17,18)产生了14063084452067724991009。
我也想在Dart中实现相同的结果。
英文:
I want to evaluate pow(17,18) in Dart language, but it produces 6665467901046659617. In Python language the same expression pow(17,18) produces 14063084452067724991009.
I want to achieve the same result in Dart also.
答案1
得分: 4
看起来Dart在某个时候出现了溢出问题，与Python不同，它不支持任意大的整数。
你可能正在使用Dart 2，它对整数有一个64位的限制。对于这个大小，最大整数是9,223,372,036,854,775,807。Dart 1有一个类似Python的整数数学实现，允许任意大小的整数（仅受可用内存限制）。
因此，你看到的值6,665,467,901,046,659,617，只是pow(17,18)对Dart 2的最大整数值取模后的结果+1。
然而，Dart 2仍然有BigInt，专门用于此目的。如用户@mmcdon20在评论中指出，你正在寻找的是：
BigInt.from(17).pow(18)
英文:
It looks like Dart runs into an overflow at some point and does not (like Python) support arbitrarily large integers.
You are likely using Dart 2, which has a limit of 64 bits for integers. The maxint for that size is 9,223,372,036,854,775,807. Dart 1 did have a similar integer math implementation to Python, allowing integers of arbitrary size (limited by available memory only).
So, it makes sense that you're seeing a value like 6,665,467,901,046,659,617, which is just the result of pow(17,18) modulo the maximum integer value for Dart 2 + 1.
However, Dart 2 still has BigInt, exactly for this purpose. As user @mmcdon20 indicated in the comments, you're looking for:
BigInt.from(17).pow(18)
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