🐏Variables

Now that we are able to accept input and print output externally, we need a mechanism to store data inside our program.

What is a Variable?

A variable is simply an named container that stores some value.

main.cpp

int x = 5;

In the example above,

• int indicates the type of the variable
• x is the name of the variable
• 5 is the value of the variable

Common Data Types

int	int age = 24	Integer (whole numbers)
double	double pi = 3.14	Floating point numbers
char	char x = 'c'	Singular character
bool	bool isGood = true	True / False
std::string	std::string name = "Benn"	Sequence of characters

⚠️ Common Pitfall

Use double quotes (" ") for strings and single quotes ' ' for characters

Declaration vs Initialisation

Declaration is when we define a variable's type and name without assigning it a value yet. Initialisation is when we give it a value.

main.cpp

int x;      // declaration
x = 10;     // assignment

int y = 10; // declaration + initialisation

Arithmetic Operators

You can also perform arithmetic operations just like how you would do in normal math:

main.cpp

int x = 10;
int y = 12;

int sum = x + y;
int difference = x - y;
int product = x * y;
double quotient = x / y; // note that we use the double here
int remainder = x % y;

int expression = ((x + y) * (x - y));

⚠️ Common Pitfall

Integer division truncates the division

So 10 / 12 = 0 instead of 0.83

Exercise

Extending from our previous exercise, we now want to support different operations beyond addition. Our mini-calculator should now be able to add, subtract, multiply and divide two numbers!