在java中，从另一个数字字符串中减去1个数字字符串的最佳方法是什么

Question

想要处理以下问题

String findDifference(String, String)
{
   str1 - str2
}

如果

   str1 = "1002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789";
   str2 = "0022446611002244661100224466110022446611002244661100224466110022446611002244661100224466110022446611002244661100224466110022446611002244661100224466110022446611";
   output = "1000010178100001017810000101781000010178100001017810000101781000010178100001017810000101781000010178100001017810000101781000010178100001017810000101781000010178"

   str1 = "1002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789100245678910024567891002456789";
   str2 = "0022446611000000000000224466110000000000002244661100000000000022446611000000000000224466110000000000002244661100000000000022446611000000000000224466110000000000002244661100000000000022446611000000000000224466110000000000";
   output = "1000010178100245678910000101781002456789100001017810024567891000010178100245678910000101781002456789100001017810024567891000010178100245678910000101781002456789100001017810024567891000010178100245678910000101781002456789"

是否有比Traversing Str1 ctr（0，n-1）更好/优化的方式Integer.parseInt（str1 [ctr]） - Integer.parseInt（str2 [ctr]）并将答案附加到输出[ctr]？

BigInteger会处理这么大的数字吗？

Answer 1

你交出了非常大的数字 - 大于int的数字。如果你想处理任意大数字（内存允许），你需要使用BigInteger：

public static String findDifference(String str1, String str2) {
    return new BigInteger(str1).subtract(new BigInteger(str2)).toString();
}

请注意，您的示例有误 - 输出不是str1 - str2的正确结果。

如果我使用这个小驱动程序：

public static void main(String[] args) {
    System.out.println(findDifference("10024567891002456789", "00224466110000000000"));
    System.out.println(findDifference("1002456789", "0022446611"));
    System.out.println(findDifference("1234567", "0111100"));
}

我收到此输出，并使用计算器验证显示这是正确的：

9800101781002456789
980010178
1123467