The various functions that are being used to search strings are as follows :

string find function	What/how it finds
find( )	Searches a string for a specified character or group of characters and returns the starting position of the first occurrence found or npos if no match is found. (npos is a const of –1 and indicates that a search failed.)
find_first_of( )	Searches a target string and returns the position of the first match of any haracter in a specified group. If no match is found, it returns npos.
find_last_of( )	Searches a target string and returns the position of the last match of any character in a specified group. If no match is found, it returns npos.
find_first_not_of( )	Searches a target string and returns the position of the first element that doesn’t match any character in a specified group. If no such element is found, it returns npos.
find_last_not_of( )	Searches a target string and returns the position of the element with the largest subscript that doesn’t match of any character in a specified group. If no such element is found, it returns npos.
rfind( )	Searches a string from end to beginning for a specified character or group of characters and returns the starting position of the match if one is found. If no match is found, it returns npos.

may of them are explained in later pages.