Data Types

Data Types

While writing program in any language, you need to use various variables to store various information. Variables are nothing but reserved memory  ocations to store values. This means that when you create a variable you reserve some space in memory.

You may like to store information of various data types like character, wide character, integer, floating point, double floating point, boolean etc. Based on the data type of a variable, the operating system allocates memory and decides what can be stored in the reserved memory. Primitive Built-in Types C++ offers the programmer a rich assortment of built-in as well as user defined data types. Following table lists down seven basic C++ data types:

Type                                 Keyword
Boolean                             bool
Character                          char
Integer                               int
Floating point                     float
Double floating point          double
Valueless                            void
Wide character                   wchar_t

Several of the basic types can be modified using one or more of these type modifiers:

signed
unsigned
short
long

The following table shows the variable type, how much memory it takes to store the value in memory, and what is maximum and minimum value which can be stored in such type of variables.
Type             Typical Bit Width             Typical Range
char                       1byte         -127 to 127 or 0 to 255
unsigned char         1byte         0 to 255
signed char             1byte         -127 to 127
int                          4bytes         -2147483648 to 2147483647
unsigned int            4bytes         0 to 4294967295
signed int               4bytes         -2147483648 to 2147483647
short int                 2bytes         -32768 to 32767
unsigned short int       Range         0 to 65,535
signed short int         Range         -32768 to 32767
long int                    4bytes     -2,147,483,647 to 2,147,483,647
signed long int         4bytes         same as long int
unsigned long int      4bytes         0 to 4,294,967,295
float                        4bytes         +/- 3.4e +/- 38 (~7 digits)
double                     8bytes         +/- 1.7e +/- 308 (~15 digits)
long double             8bytes         +/- 1.7e +/- 308 (~15 digits)
wchar_t                  2 or 4 bytes         1 wide character

The size of variables might be different from those shown in the above table,
depending on the compiler and the computer you are using.

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