Key Concepts

Review core concepts you need to learn to master this subject

Input using std::cin

Variables in C++

Arithmetic Operators

Data Type int

Data Type double

Chaining using <<

Data Type char

Data Type string

See more

Input using std::cin

int tip = 0; std::cout << "Enter amount: "; std::cin >> tip;

In C++, std::cin, which standsf or “character input”, is used to read user inputs from the keyboard.

Variables in C++

int tip = 0; std::cout << "Enter amount: "; std::cin >> tip;

In programming, a variable refers to a storage location in the computer’s memory that you can set aside to save, retrieve, and manipulate data.

Variables are denoted by a name. Value of a variable can be changed.

Arithmetic Operators

int tip = 0; std::cout << "Enter amount: "; std::cin >> tip;

C++ supports arithmetic operators for:

  • + addition
  • - subtraction
  • * multiplication
  • / division
  • % remainder

Data Type int

int tip = 0; std::cout << "Enter amount: "; std::cin >> tip;

In C++, int is a type for storing integer numbers.

Data Type double

int tip = 0; std::cout << "Enter amount: "; std::cin >> tip;

In C++, double is a type for storing floating point (decimal) numbers.

Chaining using <<

int tip = 0; std::cout << "Enter amount: "; std::cin >> tip;

In C++, std::cout can be used to output multiple values by chaining the output operator (<<).

Data Type char

int tip = 0; std::cout << "Enter amount: "; std::cin >> tip;

In C++, char is a type for storing individual characters such as 6 and !. Characters are wrapped in single quotes.

Data Type string

int tip = 0; std::cout << "Enter amount: "; std::cin >> tip;

In C++, std::string is a type for storing text strings. String are wrapped in double quotes.

Data Type bool

int tip = 0; std::cout << "Enter amount: "; std::cin >> tip;

In C++, bool is a type for storing true/false values.

Variables
Lesson 1 of 1
  1. 1
    The “Hello World!” program simply writes to the screen. It does not read anything, calculate anything, or allow for user input. That’s no fun! Real programs tend to produce results based on some …
  2. 2
    “Every variable in C++ must be declared before it can be used!” Suppose we are building a game and we want to keep track of a player’s score that goes from 0 to 10. We need a variable! Before w…
  3. 3
    After we declare a variable, we can give it a value! Suppose that we have declared an int variable called score, to set it to 0, we can simply write: score = 0; - The score is the name of the v…
  4. 4
    We can both declare and assign a value to a variable in a single initialization statement. Suppose we have these two lines: // Declare a variable int score; // Initialize a variable score = 0; …
  5. 5
    Computers are incredible at doing calculations. Now that we have declared variables, let’s use them with arithmetic operators to calculate things! Here are some arithmetic operators: - + additi…
  6. 6
    Now that we have outputted a variable and have also outputted things using multiple couts. Let’s take a closer look at cout again. If we have the code below: int age = 28; std::cout << “Hello, …
  7. 7
    Like we mentioned in the introduction, another way to assign a value to a variable is through user input. A lot of times, we want the user of the program to enter information for the program. We h…
  8. 8
    Now that we’ve learned about the basics of variables and cin, let’s write a program! The mad scientist Kelvin has mastered predicting the weather in his mountain-side meteorology lab. Recently, K…
  9. 9
    Let’s go back to the temperature.cpp that we wrote. This time, instead of giving tempf a value of the current temperature in New York: tempf = 83; Let’s ask the user what the temperature is …
  10. 10
    You made it to the end of this lesson! High five!  Here is a review of the lesson: - A variable represents a particular piece of your computer’s memory that has been set aside for you to use to …

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