programming-for-dummies

Declaring Variables 527
All integer types (int, short, and long) can also be signed or unsigned.
Signed data types can represent positive or negative numbers whereas
unsigned data types can represent only positive numbers.
Book VI
Chapter 1
To define positive values for an integer variable, you could do this:
unsigned int variablename;
The signed declaration isn’t necessary because
C and C++
signed long variablename;
is identical to
long variablename;
Table 1-1 shows the range of values common integer data types in C/C++ can
hold.
Table 1-1 Typical Storage and Range Limitations of C/C++ Integer Data Types
Data Type Number of Bytes Range
short 2 Signed: –32,768 to 32,767
Unsigned: 0 to 65,535
int 4 Signed: –2,147,483–3,648 to
2,147,483,647
Unsigned: 0 to 4,294,967,295
long 4 or 8 Signed: –2,147,483,648 to
2,147,483,647
Unsigned: 0 to 4,294,967,295
The exact number of bytes and range of all integer data types depends on
the compiler used and the operating system, such as whether you’re using a
32-bit or a 64-bit operating system. With many compilers, the range of values
is identical between int and long data types.
Declaring floating point data types
Floating point values represent decimal values, such as 3.158 or –9.4106. Just
as you can limit the range of integer values a variable can hold, so can you
limit the range of floating point values a variable can hold.
The three types of floating data types are float, double, and long double, as
shown in Table 1-2.