|
|
|
|
|
|
|
A C identifier is a name consisting of letters and digits, the
first of which must be a letter; underscore, _, counts as a letter.
A variable is an identifier that serves as the name of a chunk of computer memory. Thus, each variable refers to a chunk of memory.
The variable's data type determines the size of the chunk and the
way the bits in the chunk are interpreted. If the variable belongs to the
int data type, a kind of integer, the chunk of memory
involved is likely to contain 32 bits, which collectively determine the
integer's sign and absolute value.
The chunk of memory named by a variable is said to hold that variable's
value. As a program runs, a variable's value may change, but a
variable's data type never changes. Thus, the value of an integer variable
named size could be the integer 600 at one time and the
integer 200 at another, but size's value could never be a
floating-point number—a number that includes a decimal point—such as
10.2.