C++ data types

Basic built-in types

C++ provides programmers with a rich variety of built-in data types and user-defined data types. The following table lists the seven basic C++ data types:

Type	Keyword
Boolean Type	bool
Character type	char
Integer type	int
Float type	float
Double floating point type	double
No type	void
Wide character type	wchar_t

Some basic types can be modified using one or more type modifiers:

• signed

• unsigned

• short

• #long

The following table shows the memory required by various variable types to store values ​​in memory. , as well as the maximum and minimum values ​​that variables of this type can store.

##unsigned int4 bytes 0 to 4294967295 signed int4 bytes -2147483648 to 2147483647short int2 bytes-32768 to 32767unsigned short intRange0 to 65,535signed short intRange-32768 to 32767long int4 bytes-2,147,483,647 to 2,147,483,647signed long int4 bytesSame as long int unsigned long int4 bytes 0 to 4,294,967,295float4 bytes+/- 3.4e +/- 38 (~7 digits)double8 words section+/- 1.7e +/- 308 (~15 digits)long double8 bytes+/- 1.7e +/- 308 (~15 digits)wchar_t2 or 4 bytes1 Wide characters

As can be seen from the above table, the size of the variable will vary depending on the compiler and the computer used.

The following example will output the size of various data types on your computer.

#include <iostream>
using namespace std;

int main()
{
   cout << "Size of char : " << sizeof(char) << endl;
   cout << "Size of int : " << sizeof(int) << endl;
   cout << "Size of short int : " << sizeof(short int) << endl;
   cout << "Size of long int : " << sizeof(long int) << endl;
   cout << "Size of float : " << sizeof(float) << endl;
   cout << "Size of double : " << sizeof(double) << endl;
   cout << "Size of wchar_t : " << sizeof(wchar_t) << endl;
   return 0;
}

This example uses endl, which will insert a newline character after each line. The << operator is used to pass multiple values ​​to the screen. We also use the sizeof() function to get the size of various data types.

When the above code is compiled and executed, it produces the following results, which will vary depending on the computer used:

Size of char : 1
Size of int : 4
Size of short int : 2
Size of long int : 4
Size of float : 4
Size of double : 8
Size of wchar_t : 4

typedef declaration

You can use typedef to give an existing type a new name. The following is the syntax for using typedef to define a new type:

typedef type newname;

For example, the following statement will tell the compiler that feet is another name for int:

typedef int feet;

Now, the following declaration is completely Legal, it creates an integer variable distance:

feet distance;

Enumeration type

The enumeration type declares an optional type name and a set of identifiers used as the type value. Zero or more identifiers can be used as values ​​of this type. Each enumerator is a constant of an enumeration type.

To create an enumeration, you need to use the keyword enum. The general form of an enumeration type is:

enum enum-name { list of names } var-list;

Here, enum-name is the name of the enumeration type. The list of names { list of names } is comma separated.

For example, the following code defines a color enumeration, and the type of variable c is color. Finally, c is assigned the value "blue".

enum color { red, green, blue } c;
c = blue;

By default, the first name has a value of 0, the second name has a value of 1, the third name has a value of 2, and so on. However, you can also assign a special value to the name by adding an initial value. For example, in the following enumeration, green has a value of 5.

enum color { red, green=5, blue };

Here, blue has a value of 6 because by default, each name is 1 greater than the one before it.

Type	Bit	Range
char	1 bytes	-128 to 127 or 0 to 255
unsigned char	1 bytes	0 to 255
signed char	1 byte	-128 to 127
int	4 bytes	-2147483648 to 2147483647