Question

我有一个程序

    public void TestMethod2()
    {
        string[] keywords =
        {
            "SELECT", "FROM", "WHERE", "GROUP", "HAVING", "ORDER", "LEFT",  "RIGHT", "JOIN", "INNER", "OUTER", "ASC",
            "DESC", "AND", "OR","IN", "BETWEEN", "BY", "NOT", "ON", "AS", "CASE", "WHEN", "ELSE", "UPDATE", "SET"
        };

        var actualString = "SELECT * FROm A Join B On C in D case e join t left outer join inner join right join";

        foreach (var text in actualString.Split(' '))
        {
            var isExists = keywords.Any(x => x.Equals(text, StringComparison.OrdinalIgnoreCase));

            if (!isExists)
            {
                continue;
            }

            actualString = actualString.Replace(text, text.ToUpper());
        }


        var expectedString = "SELECT * FROM A JOIN B ON C IN D CASE e JOIN t LEFT OUTER JOIN INNER JOIN RIGHT JOIN";

    }

我是C＃的新手。我不清楚为什么 Replace（）方法没有按预期工作。它显示输出 SELECT * FROM A JOIN B ON C IN D CASE e joIN t LEFT OUTER JOIN INNER joIN RIGHT joIN

有人可以告诉我为什么Replace（）表现得像这样吗？提前致谢。

Answer 1

如果您调试它，您会注意到您的关键字＆＃34; in＆＃34;替换第二个连接，以便您获得joIN。之后您的文本变量将尝试替换＆＃34; join＆＃34;用＆＃34; JOIN＆＃34;但它不会发现＆＃34;加入＆＃34;因为它的一部分是大写的。

Answer 2

表现如预期。这是逐行输出：

[SELECT] -> SELECT * FROm A Join B On C in D case e join t left outer join inner join right join
[FROm]   -> SELECT * FROM A Join B On C in D case e join t left outer join inner join right join
[Join]   -> SELECT * FROM A JOIN B On C in D case e join t left outer join inner join right join
[On]     -> SELECT * FROM A JOIN B ON C in D case e join t left outer join inner join right join
[in]     -> SELECT * FROM A JOIN B ON C IN D case e joIN t left outer joIN INner joIN right joIN
[case]   -> SELECT * FROM A JOIN B ON C IN D CASE e joIN t left outer joIN INner joIN right joIN
[join]   -> SELECT * FROM A JOIN B ON C IN D CASE e joIN t left outer joIN INner joIN right joIN
[left]   -> SELECT * FROM A JOIN B ON C IN D CASE e joIN t LEFT outer joIN INner joIN right joIN
[outer]  -> SELECT * FROM A JOIN B ON C IN D CASE e joIN t LEFT OUTER joIN INner joIN right joIN
[join]   -> SELECT * FROM A JOIN B ON C IN D CASE e joIN t LEFT OUTER joIN INner joIN right joIN
[inner]  -> SELECT * FROM A JOIN B ON C IN D CASE e joIN t LEFT OUTER joIN INner joIN right joIN
[join]   -> SELECT * FROM A JOIN B ON C IN D CASE e joIN t LEFT OUTER joIN INner joIN right joIN
[right]  -> SELECT * FROM A JOIN B ON C IN D CASE e joIN t LEFT OUTER joIN INner joIN RIGHT joIN
[join]   -> SELECT * FROM A JOIN B ON C IN D CASE e joIN t LEFT OUTER joIN INner joIN RIGHT joIN

您可以看到当 in 被 IN 替换时，在第5行;然后 join 被 joIN

替换

但是，接下来发生的事情是，您对 Keywords.Any 的调用正常工作，并匹配 join 和 joIN ，但< em> replace 调用仍然区分大小写，并且不会进行替换。

替换是C＃区分大小写，不幸的是，.NET不提供不区分大小写的版本;但是周围有解决方案。

检查this link以获取不区分大小写的替换实现。

Answer 3

问题是你已经在连接中替换了IN。因此，当您要使用JOIN替换join时，比较将失败。（加入！=加入）

Answer 4

从这里的答案中得到一个清晰的想法。最后通过用 for 循环改变 foreach 来解决这个问题。谢谢你们。

public void TestMethod2()
{
    string[] keywords =
    {
        "SELECT", "FROM", "WHERE", "GROUP", "HAVING", "ORDER", "LEFT",  "RIGHT", "JOIN", "INNER", "OUTER", "ASC",
        "DESC", "AND", "OR","IN", "BETWEEN", "BY", "NOT", "ON", "AS", "CASE", "WHEN", "ELSE", "UPDATE", "SET"
    };

    var actualString = "SELECT * FROm A Join B On C in D case e join t left outer join inner join right join";

    var cnt = sqlTest.Split(' ').Count();
    for (int i = 0; i < cnt; i++)
    {
        var text = sqlTest.Split(' ')[i];
        var isExists = keywords.Any(x => x.Equals(text, StringComparison.OrdinalIgnoreCase));

        if (!isExists)
        {
            continue;
        }

        actualString = actualString.Replace(text, text.ToUpper());
    }


    var expectedString = "SELECT * FROM A JOIN B ON C IN D CASE e JOIN t LEFT OUTER JOIN INNER JOIN RIGHT JOIN";

}

Answer 5

我建议使用Regex.Replace代替String.Replace和

 \bKeyWord\b

pattern 以便将子字符串视为关键字，当且仅当它是整个字时才会

 select horror 
   from torro 
  where corner = 1 
     or ordain = 2

应该变成

 SELECT horror -- even if horror has two "or"
   FROM torro  -- even if torro has two "or"
  WHERE corner = 1 -- even if corner contains "or"
     OR ordain = 2 -- even if ordain contains "or"

实现：

string[] keywords = {
  "SELECT", "FROM", "WHERE", "GROUP", "HAVING", "ORDER", "LEFT",  "RIGHT",
  "JOIN", "INNER", "OUTER", "ASC", "DESC", "AND", "OR","IN", "BETWEEN", 
  "BY", "NOT", "ON", "AS", "CASE", "WHEN", "ELSE", "UPDATE", "SET"
};

var actualString = 
  "SELECT * FROm A Join B On C in D case e join t left outer join inner join right join";

foreach (var keyword in keywords)
  actualString = Regex.Replace(
    actualString,
    @"\b" + Regex.Escape(keyword) + @"\b",
    keyword.ToUpper(),
    RegexOptions.IgnoreCase);

String.Replace未按预期工作

5 个答案: