Checking if a string array contains a value and if so getting its position

Question

I have this string array   string   stringArray      text1    text2    text3    text4     string value    text3     I would like to determine if stringArray contains value  If so  I want to locate its position in the array    I don t want to use loops  Can anyone suggest how I might do this

User · Answer

string x   Hi  World   string y   x  char   whitespace   new char         t              string   fooArray   y Split whitespace       now you have an array of 3 strings y   String Join      fooArray   string   target      Hi    World    VW Slep      for  int i   0  i  lt  target Length  i          string v   target i       string results   Array Find fooArray  element   gt  element StartsWith v  StringComparison Ordinal               if  results    null        MessageBox Show results

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IMO the best way to check if an array contains a given value is to use System Collections Generic IList lt T gt  Contains T item  method the following way     IList lt string gt  stringArray  Contains value    Complete code sample   string   stringArray      text1    text2    text3    text4     string value    text3   if    IList lt string gt  stringArray  Contains value   Console WriteLine  The array contains   value   else Console WriteLine  The given string was not found in array       T   arrays privately implement a few methods of List lt T gt   such as Count and Contains  Because it s an explicit  private  implementation  you won t be able to use these methods without casting the array first  This doesn t only work for strings - you can use this trick to check if an array of any type contains any element  as long as the element s class implements IComparable   Keep in mind not all IList lt T gt  methods work this way  Trying to use IList lt T gt  s Add method on an array will fail

User · Answer

The simplest and shorter method would be the following   string   stringArray      text1    text2    text3    text4     string value    text3    if stringArray Contains value            Do something if the value is available in Array

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string   strArray      text1    text2    text3    text4     string value    text3    if Array contains strArray   value            Do something if the value is available in Array

User · Answer

you can try like this   you can use Array IndexOf     if you want to know the position also         string    arr     One   Two   Three           var target    One          var results   Array FindAll arr  s   gt  s Equals target

User · Answer

You can try this  it looks up for the index containing this element  and it sets the index number as the int  then it checks if the int is greater then -1  so if it s 0 or more  then it means it found such an index - as arrays are 0 based   string   Selection     First    Second    Third    Fourth    string Valid    Third         You can change this to a Console ReadLine   to        use user input  int temp   Array IndexOf Selection  Valid      it gets the index of  Valid                       in our case it s  Third              if  temp  gt  -1                  Console WriteLine  Valid selection                              else                               Console WriteLine  Not a valid selection

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I created an extension method for re-use      public static bool InArray this string str  string   values                if  Array IndexOf values  str   gt  -1              return true           return false          How to call it   string   stringArray      text1    text2    text3    text4     string value    text3   if value InArray stringArray         do something

User · Answer

You can use Array IndexOf   - note that it will return -1 if the element has not been found and you have to handle this case   int index   Array IndexOf stringArray  value

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You could use the Array IndexOf method   string   stringArray      text1    text2    text3    text4     string value    text3   int pos   Array IndexOf stringArray  value   if  pos  gt  -1           the array contains the string and the pos variable        will have its position in the array

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We can also use Exists   string   array      cat    dog    perl         Use Array Exists in different ways  bool a   Array Exists array  element   gt  element     perl    bool c   Array Exists array  element   gt  element StartsWith  d     bool d   Array Exists array  element   gt  element StartsWith  x

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EDIT  I hadn t noticed you needed the position as well  You can t use IndexOf directly on a value of an array type  because it s implemented explicitly  However  you can use   IList lt string gt  arrayAsList    IList lt string gt   stringArray  int index   arrayAsList IndexOf value   if  index    -1                 This is similar to calling Array IndexOf as per Darin s answer - just an alternative approach  It s not clear to me why IList lt T gt  IndexOf is implemented explicitly in arrays  but never mind

User · Answer

var index   Array FindIndex stringArray  x   gt  x    value

[c#] Checking if a string array contains a value, and if so, getting its position

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