Finds the last substring that is equal to the given character sequence. The search begins atpos and proceeds from right to left (thus, the found substring, if any, cannot begin in a position followingpos). Ifnpos or any value not smaller thansize() -1 is passed aspos, the whole string will be searched.

In all cases, equality is checked by callingTraits::eq.

[edit]Parameters

[edit]Return value

Position of the first character of the found substring ornpos if no such substring is found. Note that this is an offset from the start of the string, not the end.

If searching for an empty string (i.e.,str.size(),count, orTraits::length(s) is zero), the empty string is found immediately andrfind returns:

• pos, ifpos< size();
• size() otherwise, including the case wherepos== npos.

Otherwise, ifsize() is zero,npos is always returned.

[edit]Exceptions

If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).

[edit]Example

#include <iomanip>#include <iostream>#include <string> void print(std::string::size_type n,           std::string::size_type len,std::stringconst&s){if(n==std::string::npos)std::cout<<"not found\n";elsestd::cout<<"found: "<<std::quoted(s.substr(n, len))<<" at "<< n<<'\n';} int main(){    std::string::size_type n;std::stringconst s="This is a string"; // search backwards from end of string    n= s.rfind("is");    print(n,2, s); // search backwards from position 4    n= s.rfind("is",4);    print(n,2, s); // find a single character    n= s.rfind('s');    print(n,1, s); // find a single character    n= s.rfind('q');    print(n,1, s); // find the prefix (see also s.starts_with("This"))    n= s.rfind("This",0);    print(n,4, s);}

found: "is" at 5found: "is" at 2found: "s" at 10not foundfound: "This" at 0

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit]See also

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