在java中什麼是從另一個數字串減去1的數字字符串的最佳方式

Question

要處理以下問題

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

如果其中

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

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

難道還有比穿越STR1 CTR什麼更好的/優化的方法（0，n-1）Integer.parseInt（str1 [ctr]） - Integer.parseInt（str2 [ctr]）並將結果附加到輸出[ctr]？

BigInteger會處理這麼大的數字嗎？

Answer 1

你交出的數字非常大 - 大於int。如果你想處理任意大的數字（內存允許），你需要使用的BigInteger：

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

請注意，你的例子是錯誤的 - 輸出不是爲str1 - str2正確的結果。

如果我用這個小的驅動程序：

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

我得到這個輸出，並用計算器驗證表明，這是正確的：

9800101781002456789 
980010178 
1123467