PLC Chapter IV – Data Types
Data types in any of the language means that what are the various type of data the variables can have in that particular language. Information is stored in a computer memory with different data types. Whenever a variable is declared it becomes necessary to define data type that what will be the type of data that variable can hold.
There are two data types available in C++:
1. Primary Data Type character, integer, floating point, boolean, double floating point, void, wide character.
2. Additional Data Types typedef, enumerated.
Character Data Types
| Data Type (Keywords) | Description | Size | Typical Range |
| char | Any single character. It may include a letter, a digit, a punctuation mark, or a space. | 1 byte | -128 to 127 or 0 to 255 |
| signed char | Signed character. | 1 byte | -128 to 127 |
| unsigned char | Unsigned character. | 1 byte | 0 to 255 |
| wchar_t | Wide character. | 2 or 4 bytes | 1 wide character |
Integer Data Types
| Data Type (Keywords) | Description | Size | Typical Range |
| int | Integer. | 4 bytes | -2147483648 to 2147483647 |
| signed int | Signed integer. Values may be negative, positive, or zero. | 4 bytes | -2147483648 to 2147483647 |
| unsigned int | Unsigned integer. Values are always positive or zero. Never negative. | 4 bytes | 0 to 4294967295 |
| short | Short integer. | 2 bytes | -32768 to 32767 |
| signed short | Signed short integer. Values may be negative, positive, or zero. | 2 bytes | -32768 to 32767 |
| unsigned short | Unsigned short integer. Values are always positive or zero. Never negative. | 2 bytes | 0 to 65535 |
| long | Long integer. | 4 bytes | -2147483648 to 2147483647 |
| signed long | Signed long integer. Values may be negative, positive, or zero. | 4 bytes | -2147483648 to 2147483647 |
| unsigned long | Unsigned long integer. Values are always positive or zero. Never negative. | 4 bytes | 0 to 4294967295 |
Floating-point Data Types
| Data Type (Keywords) | Description | Size | Typical Range |
| float | Floating point number. There is no fixed number of digits before or after the decimal point. | 4 bytes | +/- 3.4e +/- 38 (~7 digits) |
| double | Double precision floating point number. More accurate compared to float. | 8 bytes | +/- 1.7e +/- 308 (~15 digits) |
| long double | Long double precision floating point number. | 8 bytes | +/- 1.7e +/- 308 (~15 digits) |
Boolean Data Type
| Data Type (Keywords) | Description | Size | Typical Range |
| bool | Boolean value. It can only take one of two values: true or false. | 1 byte | true or false |
Note: Variables sizes might be different in your pc from those shown in the above table, depending on the compiler you are using.
- Enum Data Type
This is an user defined data type having finite set of enumeration constants. The keyword ‘enum‘ is used to create enumerated data type.
Syntax:
enum enum-name {list of names} var-list;
enum mca(software, internet, seo);
- Typedef
It is used to create new data type. But it is commonly used to change existing data type with another name.
Syntax:
typedef [data_type] synonym;
or
typedef [data_type] new_data_type;
Example:
typedef int integer;
integer rollno;
