Cracking the Code: Your Ultimate Guide to C++ Variables - w9school

C++ Variables

Variables are containers that store values for data.

Within C++, there are various kinds of variables (defined by different terms) Examples include:

• int is a storage format for numbers (whole numbers) with decimals not included, like 123, -123, or 123.
• double is a floating point storage format that stores numbers, including decimals, like 19.99 or -19.99
• char is a single character storage format that stores such as "a" or "B". Values in Char are surrounded by single quotes
• string is a string that stores texts, like "Hello World". String values are enclosed by double quotes
• Bool - stores values in 2 states, true and false

Declaring (Creating) Variables

In order to create variables the type and assign an amount:

Syntax

type variableName = value;

When type is one of the C++ types (such as int) as well as variableName, which is the title given to that variable (such as myName or x). An equal sign equal sign is used to assign values to the variable.

To make a variable which will store a number, consider an example like this:

Example

Create a variable named myNum of the type int and give it the value of 15:

int myNum = 15; 
cout << myNum;

You may also declare a variable, without assigning a value, and assign the value later on:

Example

int myNum;
myNum = 15;
cout << myNum;

If you give a new value an existing variable replace the value of the previous one:

Example

int myNum = 15;  // myNum is 15
myNum = 10;  // Now myNum is 10
cout << myNum;  // Outputs 10

Now Try it Yourself.>>

Other Types

A display of different types of data:

Example

int myNum = 5;               // Integer (whole number without decimals)
double myFloatNum = 5.99;    // Floating point number (with decimals)
char myLetter = 'D';         // Character
string myText = "Hello";     // String (text)
bool myBoolean = true;       // Boolean (true or false)

Now Try it Yourself.>>

Display Variables

The the cout object is used in conjunction with the operator operator for displaying variables.

To mix text and variables Separate them using the operator:

Example

int myAge = 35;
cout << "I am " << myAge << " years old.";

Now Try it Yourself.>>

Add Variables Together

To join a variable another variable, utilize an + operator:

Example

int x = 5;
int y = 6;
int sum = x + y;
cout << sum;

Now Try it Yourself.>>

C++ Declare Multiple Variables

Declare Many Variables

To declare multiple variables of the similar kind make use of a comma separated list:

Example

int x = 5, y = 6, z = 50;
cout << x + y + z;

Now Try it Yourself.>>

One Value to Multiple Variables

You can assign the the same value to several variables in one line:

Example

int x, y, z;
x = y = z = 50;
cout << x + y + z;

Now Try it Yourself.>>

C++ Identifiers

Identifiers

Each of the C++ variables should need to identified by distinct names..

These names are referred to as identifyrs.

Identifiers may be short name (like an x, names like x and) as well as more specific names (age sum, totalVolume,).

Notice: It is recommended to utilize descriptive names to produce readable and maintainable code:

Example

// Good
int minutesPerHour = 60;

// OK, but not so easy to understand what m actually is
int m = 60;

Now Try it Yourself.>>

The most common guidelines for naming variables are:

• Names can include underscores, letters, and digits
• Names should start with a letter, or underscore (_)
• Names are case-sensitive ( myVar and myvar are two different variables)
• Names should not contain whitespaces or special characters such as ! #, #, % etc.
• Words that are reserved (like C++ keywords like the word int) are not able to be used in the form of names.

C++ Constants

Constants

If you don't want anyone else (or you) to alter variables' values, utilize your const keyword (this will mark the variable to be "constant", which means that it is unchangeable and cannot be read):

Example

const int myNum = 15;  // myNum will always be 15
myNum = 10;  // error: assignment of read-only variable 'myNum'

It is best to declare the variable to be constant if the values are likely to change:

Example

const int minutesPerHour = 60;
const float PI = 3.14;

Now Try it Yourself.>>

Overview

Dive into the World of C++ Variables

Hey, future coders! Today, we're diving deep into the magic of C++ variables. They're like superheroes in the coding world, and we're about to uncover their secrets. Get ready for an awesome journey into the heart of programming!

What's the Deal with Variables?

Okay, so variables are like boxes that hold stuff in the computer's brain. Think of them as containers where you keep important info like numbers, words, or even cool data. They're like the Lego bricks of coding – you use them to build amazing things!

Let's Start with the Basics

In C++, telling the computer you want a variable is super easy. It's like saying, "Hey, computer, I need a box for this special thing." Check it out:

int myNumber; // This is like telling the computer, "I want a box for whole numbers called 'myNumber'."

Now you've got a box named 'myNumber' ready to hold some cool numbers.

Filling Up Your Box

Once you've got your box, it's time to put something inside. This is where the real fun begins. It's like putting your favorite toys in a toy box:

myNumber = 42; // Now 'myNumber' is holding the awesome number 42.

Ta-da! You've just made your variable store a cool number.

Take Your Coding to the Next Level

Now that you're a variable superhero, go ahead and mix them up. Combine variables to create even cooler stuff:

int apples = 5; int bananas = 3; int totalFruits = apples + bananas; // Now 'totalFruits' holds the value 8

You're not just coding; you're creating magic!

In Conclusion

Great job, coding hero! You've just scratched the surface of C++ variables. They're your sidekicks in the coding adventure. Choose wisely, keep it simple, and let your imagination run wild!

Happy coding! 

Tips for Super Coding Skills

Tip #1: Pick the Right Box

In C++, you've got different types of boxes for different stuff. Need a box for numbers? Use 'int'. Want one for words? That's 'string'. Choose the right box for your treasures!

float myDecimal = 3.14; // A box for decimal numbers string greeting = "Hello, World!"; // A box for words

Imagine a room with boxes, but no labels. Chaos, right? Same goes for coding. Give your boxes good names so you always know what's inside.

int age = 25; // Good int a = 25; // Not so good

Exercises

Test yourself with C++ exercises to check if you have learnt anything or not..

You've only glimpsed into the vast world of C++ variables. Be aware that they're not only boxes. They're your tools for creating incredible things. Therefore, make wise choices and keep it all organized and don't give up!

Test Yourself