CA1847：对单个字符使用 string.Contains(char) 而不是 string.Contains(string)

public bool ContainsLetterI()
{
    var testString = "I am a test string.";
    return testString.Contains("I");
}
Public Function ContainsLetterI() As Boolean
    Dim testString As String = "I am a test string."
    Return testString.Contains("I")
End Function
可将此代码更改为使用 char 文本。
public bool ContainsLetterI()
{
    var testString = "I am a test string.";
    return testString.Contains('I');
}
Public Function ContainsLetterI() As Boolean
    Dim testString As String = "I am a test string."
    Return testString.Contains("I"c)
End Function