回答:
単一の文字を探している場合は、を使用できますString.IndexOfAny()。
任意の文字列が必要な場合、正規表現は機能しますが、「直接」それを実現する.NETメソッドについては知りません。
まあ、これはいつもあります：
public static bool ContainsAny(this string haystack, params string[] needles)
{
foreach (string needle in needles)
{
if (haystack.Contains(needle))
return true;
}
return false;
}使用法：
bool anyLuck = s.ContainsAny("a", "b", "c");||ただし、比較のチェーンのパフォーマンスに匹敵するものはありません。
public static bool ContainsAny(this string haystack, params string[] needles) { return needles.Any(haystack.Contains); }
以下は、実質的に同じですがよりスケーラブルなLINQソリューションです。
new[] { "a", "b", "c" }.Any(c => s.Contains(c))var values = new [] {"abc", "def", "ghj"};
var str = "abcedasdkljre";
values.Any(str.Contains);正規表現で試すことができます
string s;
Regex r = new Regex ("a|b|c");
bool containsAny = r.IsMatch (s);特定のStringComparison（たとえば、大文字と小文字を区別しない）を含むContainsAnyが必要な場合は、このString Extentionsメソッドを使用できます。
public static class StringExtensions
{
public static bool ContainsAny(this string input, IEnumerable<string> containsKeywords, StringComparison comparisonType)
{
return containsKeywords.Any(keyword => input.IndexOf(keyword, comparisonType) >= 0);
}
}での使用StringComparison.CurrentCultureIgnoreCase：
var input = "My STRING contains Many Substrings";
var substrings = new[] {"string", "many substrings", "not containing this string" };
input.ContainsAny(substrings, StringComparison.CurrentCultureIgnoreCase);
// The statement above returns true.
”xyz”.ContainsAny(substrings, StringComparison.CurrentCultureIgnoreCase);
// This statement returns false.文字列は文字のコレクションなので、それらに対してLINQ拡張メソッドを使用できます。
if (s.Any(c => c == 'a' || c == 'b' || c == 'c')) ...これは文字列を1回スキャンして、一致が見つかるまで文字ごとに文字列を1回スキャンするのではなく、最初の出現で停止します。
これは、たとえば文字の範囲をチェックするなど、好きな式に使用することもできます。
if (s.Any(c => c >= 'a' && c <= 'c')) ...// Nice method's name, @Dan Tao
public static bool ContainsAny(this string value, params string[] params)
{
return params.Any(p => value.Compare(p) > 0);
// or
return params.Any(p => value.Contains(p));
}Anyあらゆる人のAllために
static void Main(string[] args)
{
string illegalCharacters = "!@#$%^&*()\\/{}|<>,.~`?"; //We'll call these the bad guys
string goodUserName = "John Wesson"; //This is a good guy. We know it. We can see it!
//But what if we want the program to make sure?
string badUserName = "*_Wesson*_John!?"; //We can see this has one of the bad guys. Underscores not restricted.
Console.WriteLine("goodUserName " + goodUserName +
(!HasWantedCharacters(goodUserName, illegalCharacters) ?
" contains no illegal characters and is valid" : //This line is the expected result
" contains one or more illegal characters and is invalid"));
string captured = "";
Console.WriteLine("badUserName " + badUserName +
(!HasWantedCharacters(badUserName, illegalCharacters, out captured) ?
" contains no illegal characters and is valid" :
//We can expect this line to print and show us the bad ones
" is invalid and contains the following illegal characters: " + captured));
}
//Takes a string to check for the presence of one or more of the wanted characters within a string
//As soon as one of the wanted characters is encountered, return true
//This is useful if a character is required, but NOT if a specific frequency is needed
//ie. you wouldn't use this to validate an email address
//but could use it to make sure a username is only alphanumeric
static bool HasWantedCharacters(string source, string wantedCharacters)
{
foreach(char s in source) //One by one, loop through the characters in source
{
foreach(char c in wantedCharacters) //One by one, loop through the wanted characters
{
if (c == s) //Is the current illegalChar here in the string?
return true;
}
}
return false;
}
//Overloaded version of HasWantedCharacters
//Checks to see if any one of the wantedCharacters is contained within the source string
//string source ~ String to test
//string wantedCharacters ~ string of characters to check for
static bool HasWantedCharacters(string source, string wantedCharacters, out string capturedCharacters)
{
capturedCharacters = ""; //Haven't found any wanted characters yet
foreach(char s in source)
{
foreach(char c in wantedCharacters) //Is the current illegalChar here in the string?
{
if(c == s)
{
if(!capturedCharacters.Contains(c.ToString()))
capturedCharacters += c.ToString(); //Send these characters to whoever's asking
}
}
}
if (capturedCharacters.Length > 0)
return true;
else
return false;
}正規表現を使用できます
if(System.Text.RegularExpressions.IsMatch("a|b|c"))
trieデータ構造を調べます。