Python is Dynamic, C++ is Static

Dynamically Typed versus Statically Typed

On the surface, Python and C++ have a lot in common; for instance, you'll see that if statements, for loops, and basic mathematical expressions are quite similar.

But under the hood, Python and C++ have fundamental differences. One major difference is that C++ is statically typed whereas Python is dynamically typed.

Take a look at this Python code:

vehicle_doors = 4
vehicle_speed = 3.0
vehicle_acceleration = 1.5
vehicle_on = True
vehicle_gear = 'D'
vehicle_doors = vehicle_doors + 1

Python automatically figures out that vehicle_doors is an integer, vehicle_speed is a float, and vehicle_on is a boolean variable. Variable assignment is dynamic. In Python, you do not need to specify the type of value that will go into a variable.

Did you notice the typo "vehicle_dors" instead of "vehicle_doors"? That is legitimate python code, and it won't produce an error.

In C++, none of the above code would work. You need to declare the variable type before you define a value; therefore, C++ is a statically typed language. Below is a C++ version of the code:

int vehicle_doors;
float vehicle_speed;
float vehicle_acceleration;
char vehicle_gear;
bool vehicle_on;

vehicle_doors = 4;
vehicle_speed = 3.0;
vehicle_acceleration = 1.5;
vehicle_gear = 'D';
vehicle_on = True;

vehicle_doors = vehicle_doors + 1;

If you had typed: vehicle_dors = vehicle_doors + 1;, you would get an error. That is because the vehicle_dors variable was never defined.

Declaring Variables in a Statically Typed Language

In this quiz, you will write integer variable declarations in C++. Read through the code below and fill in the TODO sections:

Start Quiz:

// include all libraries needed
#include <iostream>

/* 	
*	These are C++ comments. There are two ways to write comments in C++.
*	Using the slash with an asterisk is one way.
*/ 

// Here is another way to write comments in C++

/* In general, C++ code is run from a file called main.cpp
* The implementation goes into a function called main().
* The main() function almost always returns a zero, which provides evidence that 
* the program ran to its end.
*/

// define main function
int main() {
    
    int integer_one;
    integer_one = 5;
    
    // TODO: Define a variable called integer_two and assign a value of 9.
    
    // TODO: Calculate the sum of integer_one and integer_two 
    // and assign the result to integer_sum
    int integer_sum;
    
    // outputs the results to standard out
    std::cout << integer_sum;
    
    return 0;
}

Variable Assignment Python vs C++

What if the quiz had been in Python instead of C++? Remember, Python is a dynamically typed language whereas C++ is statically typed. In Python, you can assign values and Python automatically figures out what type of variable you wanted to use; however, when programming in C++, you need to declare the variable type prior to assignment.

C++ Tip

In the C++ quiz, you might have written a statement like:

int integer_two;
integer_two = 9;

You can also define and assign a variable in one line of code like this:

int integer_two = 9;