Fundamental Variable Types in C++

Several other variable types are built into C++. They can be conveniently divided into integer variables (the type discussed so far), floating-point variables, and character variables.

Floating-point variables have values that can be expressed as fractions--that is, they are real numbers. Character variables hold a single byte and are used for holding the 256 characters and symbols of the ASCII and extended ASCII character sets.

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New Term: The ASCII character set is the set of characters standardized for use on computers. ASCII is an acronym for American Standard Code for Information Interchange. Nearly every computer operating system supports ASCII, though many support other international character sets as well.

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The types of variables used in C++ programs are described in Table 3.1. This table shows the variable type, how much room this book assumes it takes in memory, and what kinds of values can be stored in these variables.

Table 3.1. Variable Types. 

 

Type	Size	Values
unsigned short int	2 bytes	0 to 65,535
short int	2 bytes	-32,768 to 32,767
unsigned long int	4 bytes	0 to 4,294,967,295
long int	4 bytes	-2,147,483,648 to 2,147,483,647
int (16 bit)	2 bytes	-32,768 to 32,767
int (32 bit)	4 bytes	-2,147,483,648 to 2,147,483,647
unsigned int (16 bit)	2 bytes	0 to 65,535
unsigned int (32 bit)	2 bytes	0 to 4,294,967,295
char	1 byte	256 character values
float	4 bytes	1.2e-38 to 3.4e38
double	8 bytes	2.2e-308 to 1.8e308

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NOTE: The sizes of variables might be different from those shown in Table 3.1, depending on the compiler and the computer you are using. If your computer had the same output as was presented in Listing 3.1, Table 3.1 should apply to your compiler. If your output from Listing 3.1 was different, you should consult your compiler's manual for the values that your variable types can hold.

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