literal constants

I hate to ask newbie questions in here, but can someone please
explain to me what is the difference betwenn a literal constant
and a variable??

Here's what my book says

Quote:

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Constants

Like a variable, a constant is a data storage location used by your program. Unlike a variable, the value stored in a constant can't be changed during program execution. C has two types of constants, each with its own specific uses.

Literal Constants

A literal constant is a value that is typed directly into the source code wherever it is needed. Here are two examples:

Int count = 20;
float tax_rate = 0.28;

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I see no difference between this and a variable...

The literal constants in are just the numbers (or strings):
int count = 20;
float tax_rate = 0.28;
char *user_name = "John Johnes";

Constants are declared two ways:

Code:

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#define BLAH 1        // this is done by the compiler
                                // it substitutes BLAH for 1

// use:

if (myvar == BLAH){
 // do something
}

const int one = 1;
const char *hello = "Hi there";
// these are now constant variables - they cannot be changed

}

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