modern_cpp.md

Modern C++ (C++11 & beyond)

Old vs New

• Variable Initialization
  • int a = 1;
  • int a{1};
  • print using std::cout << a << std::endl;
• String Initialization
  • string s = "abhijit";
  • string s{"abhijit"};
  • print using std::cout << s << std::endl;
• Vector Initialization
  • 1

vector <int> v;
v.push_back(10);
v.push_back(20);

- 2

vector <int> v{10,20};

- print using

//print
std::cout << v.at(0) << std::endl;		// print 0th i.e. 1st element
std::cout << v.at(1) << std::endl;		// print 1st i.e. 2nd element
std::cout << v.at(2) << std::endl;		// Gives Error: 'std::out_of_range'

• Map initialization
  • 1

map<string, string> capitals = {
	{"UK", "london"}, {"India", "Delhi"}
};

- 2

map<string, string> capitals {
	{"UK", "london"}, {"India", "Delhi"}
};

- print using

for(auto&& i : capitals) {
	std::cout << i.first << ": " << i.second << std::endl;	
}

• Struct Initialization
  • define struct

struct Person
{
	string name;
	int age;
};

- 1

Person p = {"abhijit", 27};

- 2

Person p{"abhijit", 27};

- print using

std::cout << p.name << ", " << p.age << std::endl;

• Namespace Initialization
  • 1

namespace A {
	namespace B {
		namespace C {
			void bar(){};
		}
	}
}

- 2

namespace A::B::C {
	void bar(){};
}

- calling in main function

A::B::C::bar();