Boost string algorithms library function description 3 (FIND)

Table 11.4. Find Algorithms

 

Algorithm name	Description	Functions
Find_first	Find the first occurrence of a string in the input	Find_first () Ifind_first ()
Find_last	Find the last occurrence of a string in the input	Find_last () Ifind_last ()
Find_nth	Find the Nth (zero-indexed) occurrence of a string in the input	Find_nth () Ifind_nth ()
Find_head	Retrieve the head of a string	Find_head ()
Find_tail	Retrieve the tail of a string	Find_tail ()
Find_token	Find First Matching token in the string	Find_token ()
Find_regex	Use the regular expression to search the string	Find_regex ()
Find	Generic find Algorithm	Find ()

Basic example:

String str1 (  "A1234_first_nth_first_nth _"  )  ; Boost :  : Iterator_range < String :  : Iterator > IR;    // Find_first   // Ifind_first -- case-insensitive; Other IR = Find_first ( Str1 ,   "First"  )  ; Assert ( String ( IR . Begin (  )  , IR . End (  )  )   =  =   "First"  )  ;   // Compare strings Assert ( IR . Begin (  )   - Str1 . Begin (  )   =  =   6   &  & IR . End (  )  - Str1 . Begin (  )   =  =  6   +   5  )  ;   // View the position of the searched string To_upper ( IR )  ;   // Use iterator_range to process the searched string Assert ( Str1 =  =   "A1234_first_nth_first_nth _"  )  ; To_lower( IR )  ; Assert ( Str1 =  =   "A1234_first_nth_first_nth _"  )  ; IR = Find_first ( Str1 ,   "No"  )  ; Assert( IR . Empty (  )  )  ;   // Does not exist Assert ( String ( IR . Begin (  )  , IR . End ( )  )  . Empty (  )  )  ;   // A string can still be constructed because it does not exist. Ostringstream osstr ; Osstr <  < Find_first ( Str1 ,   "_ First _"   )  ; Assert ( Osstr . Str (  )  =  =  "_ First _"   )  ;    // Find_last -- same as findfirst, only in the opposite direction   // Ifind_last -- case-insensitive. Other values are the same as those in findlast.   // Find_nth IR = Find_nth ( Str1 ,  "Nth"  ,   1  )  ; Assert ( IR . Begin (  )   - Str1 . Begin (  )   =  =   22  ) ; IR = Find_nth ( Str1 ,   "Nth"  ,   0  )  ; Assert ( IR . Begin (  )   - Str1 . Begin(  )   =  =   12  )  ;   // Find_head   // Find_tail is in the opposite direction IR = Find_head ( Str1 ,   5  )  ; Transform ( IR. Begin (  )  , IR . End (  )  , IR . Begin (  )  , Bind2nd ( Plus <  Char  > (  )  ,   1  )  )  ; Assert ( Str1 =  =   "B2345_first_nth_first_nth _"  )  ;   // Find_token IR = Find_token ( Str1, Is_any_of (  "Irfst"  )  )  ; Assert ( String ( IR . Begin (  )  , IR . End (  ) )   =  =   "F"  )  ; IR = Find_token ( Str1 , Is_any_of (  "Xfirts"  )  , Token_compress_off )  ; Assert( String ( IR . Begin (  )  , IR . End (  )  )   =  =   "F"  )  ; IR = Find_token ( Str1 , Is_any_of (  "Irfst"  )  , Token_compress_on )  ; Assert ( String ( IR . Begin (  )  , IR. End (  )  )   =  =   "First"  )  ; IR = Find_token ( Str1 , Is_any_of (  "Fitr"  )  , Token_compress_on )  ; Assert ( String ( IR . Begin (  )  , IR . End (  )  )   =  =   "Fir" )  ;   // Find_regex Boost :  : RegEx RX (  "B [0-9] + _"  )  ; IR = Find_regex ( Str1 , RX )  ; Assert ( String( IR . Begin (  )  , IR . End (  )  )   =  =   "B2345 _"  )  ;   // Not listed in find_all_regex Test Table 11.4, which is in the boost_1_33_0 \ libs \ algorithm \ string \ test directory. String str2(  "Bda-b22_b333_b4444"  )  ; Vector < String > Tokens ; Find_all_regex ( Tokens , Str2 , RX )  ; Assert ( Tokens . Size(  )   =  =   3  )  ; Assert ( Tokens [  0  ]   =  =   "B1 _"  )  ; Assert ( Tokens[  1  ]   =  =   "B22 _"  )  ; Assert ( Tokens [  2  ]   =  =   "B333 _"  )  ;   // Find IR = Find ( Str1 , First_finder ( String (  "B2345 _"  )  )  )  ; Assert ( String ( IR . Begin ( )  , IR . End (  )  )   =  =   "B2345 _"  )  ;  ;