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.

C++ 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.

1. C++ 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;

2. C++ 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

3. C++ 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.

4. C++ 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.

5. C++ 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;

6. C++ 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.

C++ 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

C++ 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)
unsigned short 2 used for small positive integers (range 0 to 65,535)
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 12 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

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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