# string\_view *** **1. String Comparison** ```cpp std::string_view s1 = "Hello"; std::string_view s2 = "World"; if (s1 == s2) { std::cout << "Strings are equal" << std::endl; } ``` **2. String Concatenation** ```cpp std::string_view s1 = "Hello"; std::string_view s2 = ", "; std::string_view s3 = "World"; auto greeting = s1 + s2 + s3; std::cout << greeting << std::endl; // Output: Hello, World ``` **3. Substring Extraction** ```cpp std::string_view s = "This is a string"; auto substring = s.substr(4, 5); // "is a" std::cout << substring << std::endl; ``` **4. String Search** ```cpp std::string_view s = "Programming is fun"; auto pos = s.find("fun"); // 14 std::cout << "The substring 'fun' was found at position " << pos << std::endl; ``` **5. Character Access** ```cpp std::string_view s = "Hello"; char c = s[0]; // 'H' std::cout << c << std::endl; ``` **6. String Conversion to std::string** ```cpp std::string_view s = "Hello"; std::string str(s); // "Hello" std::cout << str << std::endl; ``` **7. String Conversion to char**\* ```cpp std::string_view s = "Hello"; char* cstr = s.data(); // Pointer to the beginning of the string std::cout << cstr << std::endl; // Output: Hello ``` **8. String Length** ```cpp std::string_view s = "Hello"; std::size_t len = s.size(); // 5 std::cout << len << std::endl; ``` **9. String Hashing** ```cpp std::string_view s = "Hello"; std::hash hash_fn; std::size_t hash_value = hash_fn(s); // Hash value of the string std::cout << hash_value << std::endl; ``` **10. String Format Argument** ```cpp std::string_view format = "Hello, {}!"; std::string name = "John"; std::cout << std::format(format, name) << std::endl; // Output: Hello, John! ``` **11. Regex Matching** ```cpp std::string_view input = "12345"; std::regex pattern("[0-9]+"); std::smatch match; if (std::regex_match(input, match, pattern)) { std::cout << "Input matches the pattern" << std::endl; } ``` **12. Text Parser** ```cpp std::string_view text = "Name: John Doe, Age: 30"; auto name_pos = text.find("Name: "); auto age_pos = text.find("Age: "); if (name_pos != std::string_view::npos && age_pos != std::string_view::npos) { std::cout << "Name: " << text.substr(name_pos + 6, age_pos - name_pos - 6) << std::endl; std::cout << "Age: " << text.substr(age_pos + 5) << std::endl; } ``` **13. File Reading** ```cpp std::ifstream file("myfile.txt"); std::string_view line; while (std::getline(file, line)) { std::cout << line << std::endl; } ``` **14. JSON Parsing** ```cpp std::string_view json = "{\"name\": \"John Doe\", \"age\": 30}"; auto name_pos = json.find("\"name\": "); auto age_pos = json.find("\"age\": "); if (name_pos != std::string_view::npos && age_pos != std::string_view::npos) { std::cout << "Name: " << json.substr(name_pos + 7, age_pos - name_pos - 7) << std::endl; std::cout << "Age: " << json.substr(age_pos + 6) << std::endl; } ``` **15. HTML Parsing** ```cpp std::string_view html = "

Hello World

"; auto title_pos = html.find("

"); auto title_end_pos = html.find("

"); if (title_pos != std::string_view::npos && title_end_pos != std::string_view::npos) { std::cout << "Title: " << html.substr(title_pos + 4, title_end_pos - title_pos - 4) << std::endl; } ``` **16. XML Parsing** ```cpp std::string_view xml = "John Doe30"; auto name_pos = xml.find(""); auto name_end_pos = xml.find(""); auto age_pos = xml.find(""); auto age_end_pos = xml.find(""); if (name_pos != std::string_view::npos && name_end_pos != std::string_view::npos && age_pos != std::string_view::npos && age_end_pos != std::string_view::npos) { std::cout << "Name: " << xml.substr(name_pos + 6, name_end_pos - name_pos - 6) << std::endl; std::cout << "Age: " << xml.substr(age_pos + 5, age_end_pos - age_pos - 5) << std::endl; } ``` **17. CSV Parsing** ```cpp std::string_view csv = "John Doe,30,Developer"; auto name_pos = csv.find(","); auto age_pos = csv.find(",", name_pos + 1); if (name_pos != std::string_view::npos && age_pos != std::string_view::npos) { std::cout << "Name: " << csv.substr(0, name_pos) << std::endl; std::cout << "Age: " << csv.substr(name_pos + 1, age_pos - name_pos - 1) << std::endl; std::cout << "Occupation: " << csv.substr(age_pos + 1) << std::endl; ```