C# - 如何检查字符的管道符号？

Question

我正在生成一个文件，格式如下：

=

有时第二个字符串是空的，所以我必须根据第一个字符串生成一个值。例如，如果第一个字符串是“StackOverflow”，我将生成第二个值作为“Stack Overflow”。

问题是有时第一个值会有一个竖线字符（旧平台的残余），即“18|2”。我不想在管道符号之前或之后添加空格。我有一个循环来检查第一个字符串值中的每个字符（来自上面的格式）。我想检查前一个字符是否是管道，并忽略这种情况。问题是，我不确定如何检查管道“|”字符。

编辑这是现在的代码：

private string createNewTitleFromFieldId(string fieldId) {
    if (string.IsNullOrWhiteSpace(fieldId))
        throw new ArgumentNullException();

    string newTitleValue = "";

    for (int i = 0; i < fieldId.Length; i++) {
        char currentChar = fieldId[i];
        char previousChar = i == 0 ? fieldId[i] : fieldId[i - 1];

        // Only perform checks if the current character is not the first character in the string.
        if (i != 0) {

            // If the current character is upper-case, and preceded by a lower-case character, append a preceding space.
            if (char.IsUpper(currentChar) && !char.IsUpper(previousChar))
                newTitleValue += string.Format(" {0}", currentChar);

            // If the current character is a number, but is not preceded by a number.
            else if (char.IsNumber(currentChar) && !char.IsNumber(previousChar)) 
                newTitleValue += string.Format(" {0}", currentChar);

            // If the character is a number, but preceded by a pipe "|" character.
            else if (char.IsNumber(currentChar) && char.Equals(previousChar, '|')) 
                newTitleValue += currentChar;

            // Add the current character to the Title if it does not match the above criteria.
            else newTitleValue += currentChar;
        }

        // Add the current character if the index is 0, otherwise we lose the first character.
        else newTitleValue += currentChar;
    }

    return newTitleValue;
}

所需输入/输出示例：

输入：“StackOverFlow”输出：“堆栈溢出”

in: "Stack1Over11Flow111" out: "Stack 1 Over 11 Flow 111"

输入：“Stack|1OverFlow|11”输出：“Stack|1 Over Flow|11”

Answer 1

要检查管道字符，您可以简单地使用

if (currentChar == '|')

确保您使用单引号而不是双引号来表示您正在使用一个字符。

Answer 2

如果不是寻找管道符号，您可以尝试添加空格

1. 如果前一个字符是字母，则在数字之前
2. 如果前一个字符是字母或数字，则在大写字母之前

实施

private static string Builder(string source) {
  if (string.IsNullOrEmpty(source))
    return source;

  StringBuilder result = new StringBuilder();

  for (int i = 0; i < source.Length; ++i) {
    char current = source[i];

    if (i > 0) {
      char prior = source[i - 1];

      if (char.IsLetter(prior) && char.IsDigit(current) ||
          char.IsLetterOrDigit(prior) && char.IsUpper(current))
        result.Append(' ');
    }

    result.Append(current);
  }

  return result.ToString();
}

测试

  string[] tests = new string[] {
    "StackOverFlow",
    "Stack1Over11Flow111",
    "Stack|1OverFlow|11",
  };

  foreach (var item in tests) {
    Console.WriteLine(Builder(item));
  }

结果：

Stack Over Flow
Stack 1 Over 11 Flow 111
Stack|1 Over Flow|11

Answer 3

如果块的顺序错误，你还有其他的。

在检查不是管道之前，您正在检查前一个字符是否不是数字：

交换两个 else 块轮次，输入 18|2 输出 18|2

private string createNewTitleFromFieldId(string fieldId) 
{
    if (string.IsNullOrWhiteSpace(fieldId))
        throw new ArgumentNullException();

    string newTitleValue = "";

    for (int i = 0; i < fieldId.Length; i++) {
        char currentChar = fieldId[i];
        char previousChar = i == 0 ? fieldId[i] : fieldId[i - 1];

        // Only perform checks if the current character is not the first character in the string.
        if (i != 0) {

            // If the current character is upper-case, and preceded by a lower-case character, append a preceding space.
            if (char.IsUpper(currentChar) && !char.IsUpper(previousChar)) 
            {
                    newTitleValue += string.Format(" {0}", currentChar);
            }
            // If the character is a number, but preceded by a pipe "|" character.
            else if (char.IsNumber(currentChar) && char.Equals(previousChar, '|')) {
                    newTitleValue += currentChar;
            }

            // If the current character is a number, but is not preceded by a number.
            else if (char.IsNumber(currentChar) && !char.IsNumber(previousChar)) {
                    newTitleValue += string.Format(" {0}", currentChar);
            }

            // Add the current character to the Title if it does not match the above criteria.
            else newTitleValue += currentChar;
        }

            // Add the current character if the index is 0, otherwise we lose the first character.
            else newTitleValue += currentChar;
        }

        return newTitleValue;
    }

然后您可以将两个语句合并在一起

// If the current character is upper-case, and preceded by a lower-case character, append a preceding space.
if (char.IsUpper(currentChar) && !char.IsUpper(previousChar))
{
    newTitleValue += string.Format(" {0}", currentChar);
}
// If the current character is a number, but is not preceded by a number or pipe.
else if (char.IsNumber(currentChar) && !char.IsNumber(previousChar) && !char.Equals(previousChar, '|'))
{
    newTitleValue += string.Format(" {0}", currentChar);
}
// Add the current character to the Title if it does not match the above criteria.
else newTitleValue += currentChar;

Answer 4

你可以使用String.IndexOf来判断字符串是否包含管道

如果找到则返回字符的索引，否则返回-1。

int pipePos = s.IndexOf('|');
if(pipePos != -1) {
   //do something
}

Answer 5

如果您只想在每个管道符号前添加一个空格，为什么需要循环？

        string s = "test|test";
        MessageBox.Show(s);
        s = s.Replace("|", " |");
        MessageBox.Show(s);