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# std::basic_string::rfind

From cppreference.com
< cpp‎ | string‎ | 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.

### [edit] 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

### [edit] Return value

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

### [edit] 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)

### [edit] Example

Run this code

    #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

### [edit] See also

find | find characters in the string (public member function) [edit]
find_first_of | find first occurrence of characters (public member function) [edit]
find_first_not_of | find first absence of characters (public member function) [edit]
find_last_of | find last occurrence of characters (public member function) [edit]
find_last_not_of | find last absence of characters (public member function) [edit]

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