Converting Code

When you switch programming languages, you need to learn how that language works. What we have learnt about C#, converts quite easily to C++. Let’s have a quick look at the main differences.

Different languages…

• have different naming conventions. In C# method names use PascalCase, while the equivalent functions/procedures use snake_case in C++.
• use different names for their types. C# and C++ include int, double, bool, and string.
• have different control flow statements, though most are similar. The control flow statements we have used in C# are the same in C++.
• support different capabilities when working with strings. In C# we used string interpolation to create strings, while in C++ you have to use concatenate to join together the parts of the strings.
• have different libraries. The C# and C++ languages have different libraries, but the SplashKit library is available across both languages.

Tip

We are focusing on building your mental model of programming, so the features we have explored so far are common across most imperative programming languages.

The C++ code for…

• Variable and constant declarations use the same syntax we were using in C#. Declare variables using int age; string name; and constants using const int MAX_WIDTH = 300. Our C++ coding convention will use snake_case variable names.
• Function and procedure calls use the same syntax write_line("Hello World");. Our C++ coding convention will use snake_case for function and procedure names.
• If statements remain the same as we were doing in C#.
• Switch case statements are similar, but are limited to integer values. So no more switch based on a string, for example.
• While loops remain the same as we were doing in C#.
• Do while loops remain the same as we were doing in C#.
• For loops remain the same as we were doing in C#.

Example

The following code is the C++ version of the menu code from the control flow chapter.

#include "splashkit.h"

int main()
{
  string line;
  int choice;

  do
  {
    write_line("1: Addition");
    write_line("2: Subtraction");
    write_line("3: Multiplication");
    write_line("4: Division");
    write_line("5: Quit");
    write("Enter your choice: ");
    line = read_line();

    while (!is_integer(line))
    {
      write_line("Please enter a whiole number");
      write("Enter your choice: ");
      line = read_line();
    }

    choice = stoi(line);

    switch (choice)
    {
      case 1:
        write_line("Addition");
        break;
      case 2:
        write_line("Subtraction");
        break;
      case 3:
        write_line("Multiplication");
        break;
      case 4:
        write_line("Division");
        break;
      case 5:
        write_line("Quit");
        break;
      default:
        write_line("Invalid choice");
        break;
    }
  } while (choice != 5);
}