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C++ Fundamentals for Professionals

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Explore how automatic type deduction works in C++ using the auto and decltype keywords. Understand how the compiler infers variable and function types from assigned values, simplifying type declarations and supporting lambda return type inference. This lesson helps you apply these features effectively in real C++ coding scenarios.

We'll cover the following...

Replacing basic data types

C++
#include <iostream>
#include <vector>
int func(int){ return 2011;}
int main(){
  auto i = 5;
  auto& intRef = i;             // int&
  auto* intPoint = &i;         // int*
  const auto constInt = i;     // const int
  static auto staticInt = 10;  // static int
  std::vector<int> myVec;
  auto vec = myVec;           // std::vector<int>
  auto& vecRef = vec;         // std::vector<int>&
  int myData[10];
  auto v1 = myData;           // int*
  auto& v2 = myData;          // int (&)[10]
  auto myFunc = func;          // (int)(*)(int)
  auto& myFuncRef = func;      // (int)(&)(int)
  // define a function pointer
  int (*myAdd1)(int, int) = [](int a, int b){return a + b;};
  // use type inference of the C++11 compiler
  auto myAdd2 = [](int a, int b){return a + b;};
  std::cout << "\n";
  // use the function pointer
  std::cout << "myAdd1(1, 2) = " << myAdd1(1, 2) << std::endl;
  // use the auto variable
  std::cout << "myAdd2(1, 2) = " << myAdd2(1, 2) << std::endl;
  std::cout << "\n";
}

Explanation

In the example above, the types are automatically deduced by the compiler, based ...