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C++17 in Detail: A Deep Dive

The Basics

Let's begin our study on std::string_view with a simple use case.

We'll cover the following...

Introductory Example

Let’s try a little experiment:

How many string copies are c​reated in the below example?

C++ 17
  // string function:
std::string StartFromWordStr(const std::string& strArg, const std::string& word) {
  return strArg.substr(strArg.find(word)); // substr creates a new string 
}
int main() {
  // call:
  std::string str {"Hello Amazing Programming Environment" }; 
  
  auto subStr = StartFromWordStr(str, "Programming Environment");
  std::cout << subStr << '\n';
}

Can you count them all?

The answer is 3 or 5 depending on the compiler, but usually, it should be 3.

  • The first one is for str.
  • The second one is for the second argument in StartFromWordStr - the argument is const string& so since we pass const char* it will create a new string.
  • The third one comes from substr
...