C++ Data Types

 

In C++, data types are declarations for variables. This determines the type and size of data associated with variables. For example,

int age = 13;

Here, age is a variable of type int. Meaning, the variable can only store integers of either 2 or 4 bytes.

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Fundamental Data Types

The table below shows the fundamental data types, their meaning, and their sizes (in bytes):

Data Type	Meaning	Size (in Bytes)
int	Integer	2 or 4
float	Floating-point	4
double	Double Floating-point	8
char	Character	1
wchar_t	Wide Character	2
bool	Boolean	1
void	Empty	0

Now, let us discuss these fundamental data types in more detail.

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1. int

• The int keyword is used to indicate integers.
• Its size is usually 4 bytes. Meaning, it can store values from -2147483648 to 2147483647.
• For example,

int salary = 85000;

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2. float and double

• float and double are used to store floating-point numbers (decimals and exponentials).
• The size of float is 4 bytes and the size of double is 8 bytes. Hence, double has two times the precision of float. To learn more, visit C++ float and double.
• For example,

float area = 64.74;
double volume = 134.64534;

As mentioned above, these two data types are also used for exponentials. For example,

double distance = 45E12    // 45E12 is equal to 45*10^12

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3. char

• Keyword char is used for characters.
• Its size is 1 byte.
• Characters in C++ are enclosed inside single quotes ' '.
• For example,

char test = 'h';

Note: In C++, an integer value is stored in a char variable rather than the character itself. To learn more, visit C++ characters.

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4. wchar_t

• Wide character wchar_t is similar to the char data type, except its size is 2 bytes instead of 1.
• It is used to represent characters that require more memory to represent them than a single char.
• For example,

wchar_t test = L'ם'  // storing Hebrew character;

Notice the letter L before the quotation marks.

Note: There are also two other fixed-size character types char16_t and char32_t introduced in C++11.

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5. bool

• The bool data type has one of two possible values: true or false.
• Booleans are used in conditional statements and loops (which we will learn in later chapters).
• For example,

bool cond = false;

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6. void

• The void keyword indicates an absence of data. It means "nothing" or "no value".
• We will use void when we learn about functions and pointers.

Note: We cannot declare variables of the void type.

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 Type Modifiers

We can further modify some of the fundamental data types by using type modifiers. There are 4 type modifiers in C++. They are:

1. signed
2. unsigned
3. short
4. long

We can modify the following data types with the above modifiers:

• int
• double
• char

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 Modified Data Types List

Data Type	Size (in Bytes)	Meaning
signed int	4	used for integers (equivalent to int)
unsigned int	4	can only store positive integers
short	2	used for small integers (range -32768 to 32767)
long	at least 4	used for large integers (equivalent to long int)
unsigned long	4	used for large positive integers or 0 (equivalent to unsigned long int)
long long	8	used for very large integers (equivalent to long long int).
unsigned long long	8	used for very large positive integers or 0 (equivalent to unsigned long long int)
long double	8	used for large floating-point numbers
signed char	1	used for characters (guaranteed range -127 to 127)
unsigned char	1	used for characters (range 0 to 255)

Let's see a few examples.

long b = 4523232;
long int c = 2345342;
long double d = 233434.56343;
short d = 3434233; // Error! out of range
unsigned int a = -5;    // Error! can only store positive numbers or 0

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Derived Data Types

Data types that are derived from fundamental data types are derived types. For example: arrays, pointers, function types, structures, etc.

We will learn about these derived data types in later tutorials.

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