1  
 2 #include <iostream> // std::cout
 3  
 4 #include <string> // std::string
 5  
 6  
 7  
 8 int main ()
 9  
10 {
11  
12 std::string str ("There are two needles in this haystack with needles.");
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14 std::string str2 ("needle");
15  
16  
17  
18 // different member versions of find in the same order as above:
19  
20 std::size_t found = str.find(str2);
21  
22 if (found!=std::string::npos)
23  
24 std::cout << "first 'needle' found at: " << found << '\n';
25  
26  
27  
28 found=str.find("needles are small",found+1,6);
29  
30 if (found!=std::string::npos)
31  
32 std::cout << "second 'needle' found at: " << found << '\n';
33  
34  
35  
36 found=str.find("haystack");
37  
38 if (found!=std::string::npos)
39  
40 std::cout << "'haystack' also found at: " << found << '\n';
41  
42  
43  
44 found=str.find('.');
45  
46 if (found!=std::string::npos)
47  
48 std::cout << "Period found at: " << found << '\n';
49  
50  
51  
52 // let's replace the first needle:
53  
54 str.replace(str.find(str2),str2.length(),"preposition"); //replace 用法
55  
56 std::cout << str << '\n';
57  
58  
59  
60 return 0;
61  
62 }