Question

如果我有一个字符串：

How much wood would a woodchuck chuck
if a woodchuck could chuck wood?
Just as much as a woodchuck would
if a woodchuck could chuck wood.

我希望用""替换这些字词：

wood, chuck, if

这是我的代码：

string[] words = new string[] { "wood", "chuck", "if" };
string input = woodchuckText;
string output = string.Empty;

foreach (string word in words)
{
  output = input.Replace(word, string.Empty);
}

Console.Write(output);

为什么它只替换掉最后一个单词而不是全部替换它们？

Answer 1

替换后

input永远不会改变，所以基本上你得到的输出就像你只替换了你的最后一个单词一样。

要解决此问题，请改为：

output = input;

foreach (string word in words)
 {
  output = output.Replace(word, string.Empty);
 }

Answer 2

因为您总是在Input的原始副本上进行迭代，并且在最后一次迭代中，只有最后一次替换才会生效，因此您获得了output结果

foreach (string word in words)
{
  input = input.Replace(word, string.Empty);
}
 output  =  input;

<强>提示

尝试通过按output = input.Replace(word, string.Empty);在F9上设置断点，你会看到输出是什么

或

将Console.Write(output);放在foreach循环中

foreach (string word in words) { output = input.Replace(word, string.Empty); Console.Write(output); }

Answer 3

您还可以使用正则表达式：

string[] words = new string[] { "wood", "chuck", "if" };
var output = Regex.Replace(input, String.Join("|", words), "");

Answer 4

因为每次迭代都要将output设置为原始input字符串。因此，只会在output上设置最后一次迭代。调整逻辑以保持更新相同的字符串：

string[] words = new string[] { "wood", "chuck", "if" };
string input = woodchuckText;
string output = input;

foreach (string word in words)
{
  output = output.Replace(word, string.Empty);
}

Console.Write(output);

替换字符串中的数组中的单词

4 个答案: