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std::basic_string::rfind

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< cpp‎ | string‎ | basic string
Revision as of 16:56, 26 August 2013 by P12 (Talk | contribs)

 
 
 
std::basic_string
 
size_type rfind( const basic_string& str, size_type pos = npos ) const;
(1)
size_type rfind( const CharT* s, size_type pos, size_type count ) const;
(2)
size_type rfind( const CharT* s, size_type pos = npos ) const;
(3)
size_type rfind( CharT ch, size_type pos = npos ) const;
(4)

Finds the last substring equal to the given character sequence. Search begins at pos, i.e. the found substring must not begin in a position following pos. If npos or any value not smaller than size() is passed as pos, whole string will be searched.

1) Finds the last substring equal to str. If str.size() is zero, returns pos or size()-1, whichever is smaller.
2) Finds the last substring equal to the first count characters of the character string pointed to by s. s can include null characters. If count is zero, returns pos or size()-1, whichever is smaller.
3) Finds the last substring equal to the character string pointed to by s. The length of the string is determined by the first null character. If the length of s is zero, returns pos or size()-1, whichever is smaller.
4) Finds the last character ch.

If size() is zero, npos is always returned.

Contents

Parameters

str - string to search for
pos - position at which to begin searching
count - length of substring to search for
s - pointer to a character string to seach for
ch - character to search for

Return value

Position of the first character of the found substring or npos if no such substring is found.

Exceptions

1-4) (none)
(until C++11)
1,4)
noexcept specification:  
noexcept
  
2,3) (none)
(since C++11)
(until C++14)
1)
noexcept specification:  
noexcept
  
2,3,4) (none)
(since C++14)

Example

#include <string>
#include <iostream>
 
void print(std::string::size_type n, std::string const &s)
{
    if (n == std::string::npos) {
        std::cout << "not found\n";
    } else {
        std::cout << "found: " << s.substr(n) << '\n';
    }
}
 
int main()
{
    std::string::size_type n;
    std::string const s = "This is a string";
 
    // search backwards from end of string
    n = s.rfind("is");
    print(n, s);
    // search backwards from position 4
    n = s.rfind("is", 4);
    print(n, s);
    // find a single character
    n = s.rfind('s');
    print(n, s);
    // find a single character
    n = s.rfind('q');
    print(n, s);
}

Output:

found: is a string
found: is is a string
found: string
not found

See also

find characters in the string
(public member function) [edit]
find first occurrence of characters
(public member function) [edit]
find first absence of characters
(public member function) [edit]
find last occurrence of characters
(public member function) [edit]
find last absence of characters
(public member function) [edit]