C++中find()函数和rfind()函数的用法

 1 #include <iostream>       // std::cout  
 2 #include <string>         // std::string  
 3   
 4 int main ()  
 5 {  
 6   std::string str ("There are two needles in this haystack with needles.");  
 7   std::string str2 ("needle");  
 8   
 9   // different member versions of find in the same order as above:  
10   std::size_t found = str.find(str2);  
11   if (found!=std::string::npos)  
12     std::cout << "first ‘needle‘ found at: " << found << ‘\n‘;  
13   
14   found=str.find("needles are small",found+1,6);  
15   if (found!=std::string::npos)  
16     std::cout << "second ‘needle‘ found at: " << found << ‘\n‘;  
17   
18   found=str.find("haystack");  
19   if (found!=std::string::npos)  
20     std::cout << "‘haystack‘ also found at: " << found << ‘\n‘;  
21   
22   found=str.find(‘.‘);  
23   if (found!=std::string::npos)  
24     std::cout << "Period found at: " << found << ‘\n‘;  
25   
26   // let‘s replace the first needle:  
27   str.replace(str.find(str2),str2.length(),"preposition");  //replace 用法  
28   std::cout << str << ‘\n‘;  
29   
30   return 0;  
31 }