//Execute this code and observe the output //As string is not falling inside the category of small string optimization, //it will allocate memory on heap (generally when length is more than 15) //so, first 35 bytes are due to allocation on heap by a statement string str //Second time, 35 bytes are allocated due to copy constructor called due to function printString1 //Then, there is no burden of copy constructor as printString2 is taking string reference //Then, there is no burden of copy constructor for printString3 as well is taking string string view //Now concern is on need of the string view. //const string& also allow us to avoid copy constructor and so does string view //So, what was need to introduce the string view? //I believe no need to have this additional string_view when you want to view entire string //But in case of viewing a substring from string, string view is benifical. //Observe functions printSubString2 where string.substr allocates memory on heap //where as function printSubString3 suggests that substring.view does not allocate additional memory #include #include using namespace std; void* operator new(size_t ss) { cout << "allocating " << ss << " bytes\n"; void* ptr = malloc(ss); return ptr; } void printString1(string str) { cout << str << endl; } void printString2(const string& str) { cout << str << endl; } void printString3(string_view strView) { cout << strView << endl; } void printSubString2(const string& str,size_t pos,size_t cnt) { cout << str.substr(pos,cnt) << endl; } void printSubString3(string_view strView,size_t pos,size_t cnt) { cout << strView.substr(pos,cnt) << endl; } int main() { //const char* pcc = "Ensure that this is a large string"; //cout << pcc << endl; string str = "Ensure that this is a large string"; cout << "\n\n\n"; printString1(str); cout << "\n\n\n"; printString2(str); cout << "\n\n\n"; printString3(str); cout << "\n\n\n"; printSubString2(str,7,22); cout << "\n\n\n"; printSubString3(str,7,22); cout << "\n\n\n"; return 0; }

string_view Best usecase