A Objective-C program consists of various strings.
A string is either a keyword, an identifier, a constant, a string literal, or a symbol.
In Objective-C program, the semicolon is a statement terminator.
Each statement must be ended with a semicolon.
For example, following are two different statements:
NSLog(@"Hello, World! \n");
return 0;
Comments are text in your Objective-C program to explain the meaning of a statement.
They are ignored by the compiler.
They start with /* and terminate with the characters */ as shown below:
/* my first program in Objective-C */
You cannot nest comments within comments.
An Objective-C identifier identifies a variable, a function, or other user-defined items.
An identifier starts with a letter A to Z or a to z or an underscore _ followed by zero or more letters, underscores, and digits (0 to 9).
Objective-C does not allow characters such as @, $, and % within identifiers.
Objective-C is a case-sensitive programming language.
Thus, aVaraible and AVaraible are two different identifiers in Objective-C.
Here are some examples of acceptable identifiers:
_temp a13b9 a_123 abc j m1 move_name myname50 retVal
A variable is a name given to a storage area.
Each variable in Objective-C has a specific type.
A variable definition contains a data type and a list of variables of that type.
type variable_list;
type must be a valid Objective-C data type including char,
w_char, int, float, double, bool or any user-defined object, etc.,
variable_list can have one or more identifiers separated by commas.
The following code defines int, char, float and double type variables.
int i, j, k; char c, ch; float f, salary; double d;
Variables can be initialized by assigning an initial value in their declaration.
The initializer has an equal sign followed by a constant expression.
type variable_name = value;
The following code shows how to initialize variables during declaration.
extern int d = 3, f = 5; // declaration of d and f. int d = 3, f = 5; // definition and initializing d and f. byte z = 2; // definition and initializes z. char x = 'x'; // the variable x has the value 'x'.