how to shorten code using using c++ in class with typename

To shorten code in C++ using the typename keyword in a class, you can follow these steps:

1. Identify the repetitive code that can be shortened.
2. Use a typedef or using statement with the typename keyword to create an alias for the repetitive type.
3. Replace all occurrences of the repetitive type with the alias.

Here's an example to illustrate these steps:

#include <iostream>
#include <vector>

// Step 1: Identify the repetitive code
class MyClass {
public:
  using MyVector = std::vector<int>;  // Step 2: Create an alias using typename

  void printVector(const MyVector& vec) {
    for (const auto& element : vec) {
      std::cout << element << " ";
    }
    std::cout << std::endl;
  }
};

int main() {
  MyClass obj;

  // Step 3: Replace repetitive type with alias
  MyClass::MyVector myVec = {1, 2, 3, 4, 5};
  obj.printVector(myVec);

  return 0;
}

In this example, we have a class MyClass that contains a method printVector() which takes a std::vector<int> as an argument. The repetitive code is the long type name std::vector<int>.

To shorten the code, we follow the steps mentioned above.

Step 2: We create an alias MyVector using the using statement with the typename keyword. This creates a shorthand for the type std::vector<int>.

Step 3: We replace all occurrences of the repetitive type std::vector<int> with the alias MyVector. This makes the code shorter and easier to read.

The resulting code is more concise and maintains readability.