這段代碼爲什麼給我一個奇怪的輸出

-6

下面的方法是爲編寫一個字符串版本的數字而編寫的，我知道已經有方法可以做到這一點，比如String.valueOf(),Double.toString()，或者甚至只是"" + someNumber。這段代碼爲什麼給我一個奇怪的輸出

private static String numToString(double i) { 
      String revNumber = ""; 
      boolean isNeg = false; 
      if (i == 0) { //catch zero case 
       return "0"; 
      } 

      if (i < 0) { 
       isNeg = true; 
      } 

      i = Math.abs(i); 
      while (i > 0) { //loop backwards through number, this loop 
       //finish, otherwise, i would not get any output in 'main()' 
       revNumber += "" + i % 10; //get the end 
       i /= 10; //slice end 
      } 

      String number = ""; //reversed 
      for (int k = revNumber.length() - 1; k >= 0; k--) { 
       number += revNumber.substring(k, k + 1); 
      } 

      revNumber = null; //let gc do its work 

      return isNeg ? "-" + number : number; //result expression to add "-" 
      //if needed. 
     }

儘管上述方法應當僅被用於整數（32位），I使它接受雙（64位）的參數和我經過一個double參數，不帶小數點，輸出結果是相同的，如果我傳遞一個INT到方法爲好，或有小數等...

測試：

public static void main(String[] args) { 
    double test = -134; //Passing double arg 
    System.out.println(numToString(test)); //results 
}

結果：（最大內存結果雙）：

-323-E5.1223-E33.1123-E43.1023-E43.1913-E43.1813-E43.1713-E43.1613-E43.1513-E43.1413-E43.1313-E43.1213 -E43.1113-E43.1013-E43.1903-E43.1803-E999999999999933.1703-E999999999999933.1603-E999999999999933.1503-E999999999999933.1403-E9899999999999933.1303-E999999999999933.1203-E999999999999933.1103-E8899999999999933.1003-E9899999999999933 0.1992-E999999999999933.1892-E999999999999933.1792-E999999999999933.1692-E999999999999933.1592-E999999999999933.1492-E999999999999933.1392-E999999999999933.1292-E999999999999933.1192-E999999999999933.1092-E999999999999933.1982-E999999999999933.1882-E1999999999999933.1782 -E999999999999933.1682-E999999999999933.1582-E999999999999933.1482-E999999999999933.1382-E999999999999933.1282-E1999999999999933.1182-E1999999999999933.1082-E2999999999999933.1972-E2999999999999933.1872-E3999999999999933.1772-E2999999999999933.1672-E1999999999999933.1572-E2999999999999933 .1472- E999999999999933.1372-E999999999999933.1272-E1999999999999933.1172-E2999999999999933.1072-E2999999999999933.1962-E1999999999999933.1862-E999999999999933.1762-E999999999999933.1662-E999999999999933.1562-E999999999999933.1462-E999999999999933.1362-E999999999999933.1262-E999999999999933。 1162-E999999999999933.1062-E999999999999933.1952-E999999999999933.1852-E999999999999933.1752-E999999999999933.1652-E999999999999933.1552-E999999999999933.1452-E999999999999933.1352-E999999999999933.1252-E999999999999933.1152-E999999999999933.1052-E9899999999999933.1942- E9899999999999933.1842-E999999999999933.1742-E999999999999933.1642-E999999999999933.1542-E999999999999933.1442-E999999999999933.1342-E999999999999933.1242-E999999999999933.1142-E9899999999999933.1042-E999999999999933.1932-E8899999999999933.1832-E9899999999999933.1732-E8899999999999933。 1632 - E8899999999999933.1532-E8899999999999933.1432-E999999999999933.1332-E9899999999999933.1232-E8899999999999933.1132-E7899999999999933.1032-E8899999999999933 0.1922-E8899999999999933.1822-E7899999999999933.1722-E6899999999999933.1622-E5899999999999933.1522-E5899999999999933.1422-E6899999999999933.1322-E6899999999999933.1222-E6899999999999933.1122-E7899999999999933.1022-E7899999999999933.1912-E7899999999999933.1812-E8899999999999933.1712 -E8899999999999933.1612-E7899999999999933.1512-E7899999999999933.1412-E6899999999999933.1312-E6899999999999933.1212-E7899999999999933.1112-E7899999999999933.1012-E7899999999999933.1902-E7899999999999933.1802-E6899999999999933.1702-E7899999999999933.1602-E7899999999999933.1502-E8899999999999933 0.1402-E8899999999999933.1302-E8899999999999933.1202-E8899999999999933.1102-E7899999999999933.1002-E7899999999999933.1991-E9899999999999933.1891-E9899999999999933.1791-E8899999999999933.1691-E7899999999999933.1591-E8899999999999933.1491-E8899999999999933.1391-E999999999999933.1291 -E9899999999999933.1191-E9899999999999933.1091-E999999999999933.1981-E999999999999933.1881-E999999999999933.1781-E999999999999933.1681-E999999999 999933.1581-E1999999999999933.1481-E999999999999933.1381-E999999999999933.1281-E1999999999999933.1181-E2999999999999933.1081-E999999999999933.1971-E1999999999999933.1871-E999999999999933.1771-E2999999999999933.1671-E3999999999999933.1571-E3999999999999933.1471-E2999999999999933.1371- E2999999999999933.1271-E2999999999999933.1171-E999999999999933.1071-E999999999999933.1961-E999999999999933.1861-E999999999999933.1761-E999999999999933.1661-E999999999999933.1561-E999999999999933.1461-E8899999999999933.1361-E8899999999999933.1261-E8899999999999933.1161-E7899999999999933。 1061 - E7899999999999933.1951-E7899999999999933.1851-E7899999999999933。1751-E7899999999999933.1651-E7899999999999933.1551-E6899999999999933.1451-E6899999999999933.1351-E6899999999999933.1251-E6899999999999933.1151-E6899999999999933.1051-E7899999999999933.1941-E6899999999999933.1841-E7899999999999933.1741-E7899999999999933.1641-E9899999999999933.1541- E999999999999933.1441-E999999999999933.1341-E999999999999933.1241-E999999999999933.1141-E999999999999933.1041-E999999999999933.1931-E9899999999999933.1831-E999999999999933.1731-E999999999999933.1631-E8899999999999933.1531-E9899999999999933.1431-E9899999999999933.1331-E8899999999999933。 1231-E8899999999999933.1131-E8899999999999933.1031-E7899999999999933.1921-E7899999999999933.1821-E7899999999999933.1721-E6899999999999933.1621-E7899999999999933.1521-E7899999999999933.1421-E8899999999999933.1321-E7899999999999933.1221-E7899999999999933.1121-E8899999999999933.1021- E8899999999999933.1911-E9899999999999933.1811-E999999999999933.1711-E999999999999933.1611-E999999999999933.1511-E999999999999933.1411-E1999999999999933。 1311-E2999999999999933.1211-E3999999999999933.1111-E2999999999999933.1011-E2999999999999933.1901-E3999999999999933.1801-E2999999999999933.1701-E2999999999999933.1601-E3999999999999933.1501-E2999999999999933.1401-E3999999999999933.1301-E3999999999999933.1201-E4999999999999933.1101- E5999999999999933.1001-E4999999999999933.199-E3999999999999933.189-E3999999999999933.179-E3999999999999933.169-E4999999999999933.159-E4999999999999933.149-E4999999999999933.139-E4999999999999933.129-E4999999999999933.119-E4999999999999933.109-E4999999999999933.198-E4999999999999933。 188 E4999999999999933.178-E3999999999999933.168-E3999999999999933.158-E3999999999999933.148-E3999999999999933.138-E3999999999999933.128-E4999999999999933.118-E3999999999999933.108-E3999999999999933.197-E3999999999999933.187-E3999999999999933.177-E4999999999999933.167- E3999999999999933.157-E3999999999999933.147-E3999999999999933.137-E3999999999999933.127-E3999999999999933.117-E4999999999999933.107-E5999999999999933.196-E5999999999999 933.186-E5999999999999933.176-E4999999999999933.166-E4999999999999933.156-E4999999999999933.146-E4999999999999933.136-E3999999999999933.126-E3999999999999933.116-E3999999999999933.106-E3999999999999933.195-E2999999999999933.185-E1999999999999933.175-E2999999999999933.165- E2999999999999933.155-E2999999999999933.145-E2999999999999933.135-E3999999999999933.125-E4999999999999933.115-E4999999999999933.105-E2999999999999933.194-E1999999999999933.184-E2999999999999933.174-E2999999999999933.164-E2999999999999933.154-E1999999999999933.144-E1999999999999933。 134-E2999999999999933.124-E2999999999999933.114-E2999999999999933.104-E3999999999999933.193-E3999999999999933.183-E3999999999999933.173-E2999999999999933.163-E2999999999999933.153-E999999999999933.143-E2999999999999933.133-E2999999999999933.123-E2999999999999933.113- E3999999999999933.103-E3999999999999933.192-E3999999999999933.182-E3999999999999933.172-E3999999999999933.162-E4999999999999933.152-E4999999999999933.142-E5999999999999933.132-E69 99999999999933.122-E7999999999999933.112-E6999999999999933.102-E6999999999999933.191-E7999999999999933.181-E8999999999999933.171-E8999999999999933.161-E8999999999999933.151-E9999999999999933.141-E8999999999999933.131-E8999999999999933.121-E43.111-E43.101- E43.19-E1000000000000043.18-E1000000000000043.17-E43.16-E43.15-E43.14-E43.143100.04310.0431.043.14000000000000004.30.4

來源

2015-07-21 WIll

我從來沒有在你的循環中小於0。 – Adam

'我/ = 10'不會「分片結束」一倍。 – JJJ

這可能適用於int，但不確定這可以用於雙打。你如何處理小數點？ –

這不是編譯的，因爲。它發生，因爲你正在做

i /= 10; //slice end

所以，當你第一次運行後執行13.4它不會給你1.34，它會給你像1.339999999999999999是1.34。

檢查Retain precision with double in Java瞭解更多詳情。

如果你只是想扭轉數，你可以做

private static String numToString(double i) { 
     String returnString = new StringBuilder(Double.toString(i)).reverse().toString(); 
     return i>=0?returnString:"-"+returnString.substring(0,returnString.length()-1); 
}

來源

2015-07-21 19:23:33 StackFlowed

這可能是真的，但與問題沒有任何關係。問題在於循環的中斷條件是（i> 0），這是理論上永遠不會達到的。如果值正好是1.34或1.33999 ......因爲它仍然> 0，這並不重要。 – JJJ

這根本就不是問題*：「i」的值只用於「i％10」操作這不受影響。 – JJJ

@Juhana請嘗試此代碼與突破條件i> 1它仍然是一個問題！我試了一下，結果是-43.14000000000000004.30.4。你能解釋爲什麼會發生？ – StackFlowed

for (; i > 0;) { //loop backwards through number 
    revNumber += "" + i % 10; //get the end 
    i /= 10; //slice end 
}

這個循環永遠無法完成，直到它打破了在更晚的時間比它應該。 i % 10不切斷雙重結束。它與int但不具有雙重效果很好。因此，134-b> 13.4-> 1.34 - > 134->等....所以，你得到一個argumentoutofrange異常或類似的東西。否則，編譯器會繼續爲雙精度處理的最大內存做這件事。

來源

2015-07-21 19:23:55 Adam

這段代碼爲什麼給我一個奇怪的輸出

回答

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