fig08_09.cpp

// fig08_09.cpp
// C++17 string_view.
#include <fmt/format.h> 
#include <iostream>
#include <string>
#include <string_view> 

int main() {
   std::string s1{"red"};
   std::string s2{s1};
   std::string_view v1{s1}; // v1 "sees" the contents of s1
   std::cout << fmt::format("s1: {}\ns2: {}\nv1: {}\n\n", s1, s2, v1);

   // string_views see changes to the characters they view
   s1.at(0) = 'R'; // capitalize s1
   std::cout << fmt::format("s1: {}\ns2: {}\nv1: {}\n\n", s1, s2, v1);

   // string_views are comparable with strings or string_views
   std::cout << fmt::format("s1 == v1: {}\ns2 == v1: {}\n\n",
      s1 == v1, s2 == v1);

   // string_view can remove a prefix or suffix
   v1.remove_prefix(1); // remove one character from the front
   v1.remove_suffix(1); // remove one character from the back
   std::cout << fmt::format("s1: {}\nv1: {}\n\n", s1, v1);

   // string_views are iterable
   std::string_view v2{"C-string"};
   std::cout << "The characters in v2 are: ";
   for (char c : v2) {
      std::cout << c << " ";
   }

   // string_views enable various string operations on C-Strings
   std::cout << fmt::format("\n\nv2.size(): {}\n", v2.size());
   std::cout << fmt::format("v2.find('-'): {}\n", v2.find('-'));
   std::cout << fmt::format("v2.starts_with('C'): {}\n",
      v2.starts_with('C'));
}


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