// string::rfind
#include <iostream>
#include <string>
using namespace std;
int main ()
{
string str ("The sixth sick sheik's sixth sheep's sick.");
string key ("sixth");
size_t found;
found=str.rfind(key);
if (found!=string::npos)
str.replace (found,key.length(),"seventh");
cout << str << endl;
return 0;
}
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