Key Concepts

Review core concepts you need to learn to master this subject

Variable in memory.

int a; // declaring a variable a = 10 ; // assigning a value, stored in memory

A variable in a computer programming language refers to a storage location in memory. Variables are denoted by a name. Value of a variable can be changed.

Lesson 1 of 1
  1. 1

    The “Hello World!” program just 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 in…

  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 […] variable called […] , to set it to 0, we can simply write: […] - The […] is the name of t…

  4. 4

    We can both declare and assign a value to a variable in a single initialization statement. Suppose we have these two lines: […] We can actually combine these two lines into a single line of…

  5. 5

    Computers are incredible at doing calculations. Now that we have declared variables, let’s use them and arithmetic operators to calculate things! Here are some arithmetic operators: - […] a…

  6. 6

    Now that we have outputted a variable and have also outputted things using multiple […] s. Let’s take a closer look at […] again. If we have the code below: […] It will output: […..

  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 […] , let’s write a program! The mad scientist Kelvin has mastered predicting the weather in his mountain-side meteorology lab. Recentl…

  9. 9

    Let’s go back to the temperature.cpp that we wrote. This time, instead of giving […] a value of the current temperature in New York: […] Let’s ask the user what the temperature is usi…

  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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