How to check if a String contains any of some strings

Question

I want to check if a String s  contains  a  or  b  or  c   in C   I am looking for a nicer solution than using  if  s contains  a    s contains  b    s contains  c

User · Accepted Answer

If you are looking for single characters, you can use String.IndexOfAny().

If you want arbitrary strings, then I'm not aware of a .NET method to achieve that "directly", although a regular expression would work.

User · Answer

List lt string gt  includedWords   new List lt string gt       a    b    c     bool string contains words   includedWords Exists o   gt  s Contains o

User · Answer

var values   new      abc    def    ghj    var str    abcedasdkljre   values Any str Contains

User · Answer

You can use Regular Expressions  if System Text RegularExpressions IsMatch  a b c

User · Answer

Nice method s name   Dan Tao  public static bool ContainsAny this string value  params string   params        return params Any p   gt  value Compare p   gt  0          or     return params Any p   gt  value Contains p        Any for any  All for every

User · Answer

This is a  nicer solution  and quite simple  if new string      A    B         Any s  gt myString Contains s

User · Answer

You can try with regular expression  string s  Regex r   new Regex   a b c    bool containsAny   r IsMatch  s

User · Answer

If you re looking for arbitrary strings  and not just characters  you can use an overload of IndexOfAny which takes string arguments from the new project NLib   if  s IndexOfAny  aaa    bbb    ccc   StringComparison Ordinal   gt   0

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As a string is a collection of characters  you can use LINQ extension methods on them   if  s Any c   gt  c     a     c     b     c     c          This will scan the string once and stop at the first occurance  instead of scanning the string once for each character until a match is found   This can also be used for any expression you like  for example checking for a range of characters   if  s Any c   gt  c  gt    a   amp  amp  c  lt    c

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If you need ContainsAny with a specific StringComparison  for example to ignore case  then you can use this String Extentions method   public static class StringExtensions       public static bool ContainsAny this string input  IEnumerable lt string gt  containsKeywords  StringComparison comparisonType                return containsKeywords Any keyword   gt  input IndexOf keyword  comparisonType   gt   0             Usage with 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

User · Answer

Well  there s always this   public static bool ContainsAny this string haystack  params string   needles        foreach  string needle in needles                if  haystack Contains needle               return true             return false      Usage   bool anyLuck   s ContainsAny  a    b    c      Nothing s going to match the performance of your chain of    comparisons  however

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public static bool ContainsAny this string haystack  IEnumerable lt string gt  needles        return needles Any haystack Contains

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static void Main string   args                string illegalCharacters           amp           lt  gt           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  gt  0                return true          else             return false

User · Answer

Here s a LINQ solution which is virtually the same but more scalable   new      a    b    c    Any c   gt  s Contains c

[c#] How to check if a String contains any of some strings

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