string::find


public member function
size_t find ( const string& str, size_t pos = 0 ) const;
size_t find ( const char* s, size_t pos, size_t n ) const;
size_t find ( const char* s, size_t pos = 0 ) const;
size_t find ( char c, size_t pos = 0 ) const;

Find content in string

Searches the string for the content specified in either str, s or c, and returns the position of the first occurrence in the string.

When pos is specified the search only includes characters on or after position pos, ignoring any possible occurrences in previous locations.

Notice that unlike member find_first_of, whenever more than one character is being searched for, it is not enough that only one of these characters match, but the entire sequence of characters to find must be matched.

Parameters

str
string to be searched for in the object. The entire content of str must be matched in some part of the string to be considered a match.
s
Array with a sequence of characters.
In the second member function version, the size of the content to be matched is only determined by parameter n.
In the third version, a null-terminated sequence is expected, therefore its end is determined by the first occurrence of a null character in it.
n
Length of sequence of characters to search for.
c
Individual character to be searched for.
pos
Position of the first character in the string to be taken into consideration for possible matches. A value of 0 means that the entire string is considered.


Return Value

The position of the first occurrence in the string of the searched content.
If the content is not found, the member value npos is returned.

Example

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// string::find
#include <iostream>
#include <string>
using namespace std;

int main ()
{
  string str ("There are two needles in this haystack with needles.");
  string str2 ("needle");
  size_t found;

  // different member versions of find in the same order as above:
  found=str.find(str2);
  if (found!=string::npos)
    cout << "first 'needle' found at: " << int(found) << endl;

  found=str.find("needles are small",found+1,6);
  if (found!=string::npos)
    cout << "second 'needle' found at: " << int(found) << endl;

  found=str.find("haystack");
  if (found!=string::npos)
    cout << "'haystack' also found at: " << int(found) << endl;

  found=str.find('.');
  if (found!=string::npos)
    cout << "Period found at: " << int(found) << endl;

  // let's replace the first needle:
  str.replace(str.find(str2),str2.length(),"preposition");
  cout << str << endl;

  return 0;
}


Notice how parameter pos can be used to search for a second instance of the same search string. Output:
first 'needle' found at: 14
second 'needle' found at: 44
'haystack' also found at: 30
Period found at: 51
There are two prepositions in this haystack with needles.


Basic template member declarations

( basic_string<charT,traits,Allocator> )
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typedef typename Allocator::size_type size_type;
size_type find ( const basic_string& str, size_type pos = 0 ) const;
size_type find ( const charT* s, size_type pos, size_type n ) const;
size_type find ( const charT* s, size_type pos = 0 ) const;
size_type find ( charT c, size_type pos = 0 ) const;


See also

string::rfind Find last occurrence of content in string (public member function)
string::find_first_of Find character in string (public member function)
string::find_last_of Find character in string from the end (public member function)
string::find_first_not_of Find absence of character in string
string::find_last_not_of Find absence of character in string from the end (public member function)
string::replace Replace part of string (public member function)
string::substr Generate substring (public member function)