In C++, primitive data types are the built-in types that form the backbone of programming. Like a chemical compound, where different elements combine to form a large complex structure, in programming different data types combine to form complex algorithms and structures. Understanding them is pivotal in mastering C++. Here are some of the common data types:

• int: Used for storing an integer. For example, if you are tracking the number of transactions in a blockchain, you might use int.

• float: Used for storing decimal numbers. For example, when you need to store the price of a stock, float can be useful.

• bool: This is a boolean type and can hold either true or false. It's often used in logical operations or loops.

• char: Used for storing a single character. This could be part of a piece of string data, like the name of a company for a finance application.

You can declare a variable by specifying its type, followed by the variable name. For instance, int count; declares a variable named count of type int. The variable can then be assigned a value using the assignment operator (=). For example: count = 10;.

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#include <iostream>

using namespace std;

int main() {

  int transactions = 100;

  float stock_price = 200.50;

  bool isProfit = true;

  char company_name_initial = 'A';

​

  cout << transactions << endl;

  cout << stock_price << endl;

  cout << isProfit << endl;

  cout << company_name_initial << endl;

}

We've learned that we can assign values to a variable, whose type we've declared. We can modify this value as per our requirement; hence, it is called a variable in namesake.

The syntax is [data type] [variable name] = [value]; such as int stockPriceToday = 150;. The value of stockPriceToday will remain 150 until it's changed manually in the code. Similarly, stockPriceToday = 155; changes its value to 155.

C++ also allows us to declare constants using const keyword. A constant is similar to a variable, but its value remains unchanged throughout the execution of a program. It's used when you want to safeguard the value and ensure it's not getting modified by code. An example is const int stockPriceYesterday = 145;. It cannot be modified later in the code.

Every variable and constant in C++ has a certain scope and lifetime which determines its accessibility and when it's deallocated from the memory. In the next screen, we will delve deeper into the scope and lifetime of variables and constants.

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#include <iostream>

using namespace std;

​

int main() {

  int stockPriceToday = 150; // declaration of variable

  cout << "Yesterday's Stock Price: " << stockPriceToday << endl;

  stockPriceToday = 155; // modification of variable

  cout << "Today's Stock Price: " << stockPriceToday << endl;

​

  const int stockPriceYesterday = 145; // declaration of a constant

  cout << "The stock price cannot be changed: " << stockPriceYesterday << endl;

​

  return 0;

}

Based on what we learned about C++ primitive data types, variables and constants, let's look at an example that could apply to a seasoned software engineer's life.

Assume we are organizing a series of learning sessions on C++, where sessionsConducted is an integer representing the number of sessions held till date. avgRating is a float representing the average participant rating for these sessions. To mark the start of the sessions, we've defined a character type initialLetter starting with 'A'. Also, isLearningCpp is a boolean indicating whether the user is currently learning C++ or not.

The C++ code snippet provided shows how to declare these variables, assign values, and print the variables using cout. After running this code, you'll see printed details about these defined variables on the console. This gives you a hands-on understanding of working with different data types and variables in C++.

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#include <iostream>

using namespace std;

​

int main() {

  // Declaring integer type variable

  int sessionsConducted = 50;

​

  // Declaring float type variable

  float avgRating = 4.7;

​

  // Declaring char type variable

  char initialLetter = 'A';

​

  // Declaring boolean type variable

  bool isLearningCpp = true;

​

  // Printing the variables

  cout << "Sessions conducted: " << sessionsConducted << endl;

  cout << "Average rating: " << avgRating << endl;

  cout << "Initial letter: " << initialLetter << endl;

  cout << "Learning C++: " << isLearningCpp << endl;

​

  return 0;

}