Remember this piece of code?
| /* Comment: The program structure
of a basic c++ program has the following. */ #include
<iostream.h>
main () {
int number1, number2, answer;
number1=5;
number2=7;
answer=number1+number2;
cout << "The answer is" << answer << endl;
} |
We have talked about comments, now lets discuss declarations and variables.
Declarations
 | Declarations are used to describe the number and type of arguments passed to functions
or subprograms. They are also used to make new variables. |
| The code piece: int number1, number2, answer. |
| This was used to make three integers: number1, number2, and answer. |
Format of Variables
| Identifiers (symbolic variables) |
| May be composed of letters, digits, and underscore |
| First character must be letter or underscore |
| Any letter, digit or underscore may follow |
| Upper and lower case letters are distinct |
| Examples: d, digit, Digit, num1, SumDigit, sum_digit, _num |
| Length is system dependent |
| Reserved words can not be used as a program identifier |
| Library identifiers may be used as programs |
| A variable is a declaration and definition |
| Types |
 | int |
| short |
| long |
| unsigned |
| float |
| double |
| char |
| Separated by commas, or an initialization statement |
| Examples |
| int count; |
| float average, total; |
| Gives name and specifies use; may assign initial value |
| May be placed anywhere in program |
| Scope is within block in which identifier is declared |
| If declared "above" main, then it is a global variable |
Other Data Types
| Strings |
| Pointers |
| Structures |
| Arrays |
|
