正则表达式匹配所有文本而没有部分

Question

I am trying to write regular expression which will match all lines ending with: XYZ except lines which ending with AAXYZ .

Some examples:

1. ABCXYZ - should be matched
2. AAXYZ - should NOT be matched
3. ABXYZ - should be matched

I started with following expression .*[^A][^A]XYZ$ but it does not work for example 3

Answer 1

String[] lines=Regex.Split(input,"[\r\n]+")
                    .Where(x=>Regex.IsMatch(x,"^(?=.*(?<!AA)XYZ$).*$"))
                    .Select(x=>x.Value)
                    .ToArray();

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If you need only regex

^(?=.*(?<!AA)XYZ$).*$

Answer 2

A regex seems like overkill here:

var matches = myInput.Split(new[] {'\n'}, StringSplitOptions.RemoveEmptyEntries)
                     .Where(x => x.EndsWith("XYZ") && !x.EndsWith("AAXYZ"))
                     .ToList();

---

If you need a regex, you could do something like:

^(|.|.*[^A].|.+[^A])XYZ$

This simply expands all the possibilities in a pipe-deliminated alternation:

• Simply XYZ
• Any single character followed by XYZ (eg AXYZ )
• Zero or more characters followed by a non-A and one more character then XYZ (eg QAXYZ , foobarBAXYZ )
• One or more characters followed by a non-A and XYZ (eg XBXYZ , foobarXYZ )