Data Types -Objective-C

Data Types

         In the Objective-C prgramming language, data types refer to an extensive system used for declaraing Variables or functions of different types. The type of a variable determines how much space it occupies in storage and how the bit pattern stored is interpreted.

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The types in Objective-C can be classified as follows:
  1. Basic Tpes:
      They are arithmatic types and consist of the two types:
              (a)Integer types and
              (b)floating-point types.

  2. Enumerated Types:
         They are again arithmatic types and they are used to define variables that can only be assigned certain discrete integer values throughout the program.

  3. The Type void:
      The type specifier void indicates that no value is available.

 4. Derived Type:
      They include ,
             (a) Pointer types,
             (b) Array types,
             (c) Structure types,
             (d) Union types,
             (e) Function types .
  
         The array types and structure type are referred to collectively as the aggregate types. The type of a function the type of the function's return value. We will see basic types in the following sections.

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Integer Types
         Following table gives you details about standard integer types with its storage size and value ranges:
Type                                        Storage size                        Value range
char                                         1 byte                                  -128 to 127 or 0 to 255
unsigned char                          1 byte                                   0 to 255
signed char                              1 byte                                  -128 to 127
int                                            2 or 4 bytes                          -32,768 to 32,767   or
                                                                                             -2,147,483,648 to  2,147,483,647
unsigned int                            2 or 4 bytes                           0 to 65,535 or 0 to 4,294,967,295
short                                        2 bytes                                  -32,768 to 32,767
unsigned short                        2 bytes                                   0 to 65,535
long                                        4 bytes                                  -2,147,483,648 to 2,147,483,647
unsigned long                         4 bytes                                   0 to 4,294,967,295

          To get the exact size of a type or a variable on a particular plateform, you can use the sizeof operator. The expression sizeof(type) , yeilds the storage size of the object or type in bytes.
Example

#import <foundation/Foundation.h>
int main(){
    NSLog(@"Storage size for int :%d \n", sizeof(int))l
    return 0;
}
          when you compile and executes the above program , it produces the following result.

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Floating-Point Types

       Following table gives you details about standard float-types with storage sizes and value ranges and their precision.

Type                Storage size        Value range                            Precision
float                4 bytes                 1.2E-38 to 3.4E+38               6 decimal places
double             8 bytes                 2.3E-308 to 1.7E+308          15 decimal places
long double    10 bytes               3.4E-4932 to 1.1E+4932       19 decimal places

       The header file float.h defines macros that allow you to use these values and other details about the binary representation of real numbers in you programs.

#import<Foundation/Foundation.h>
int main(){
    NSLog(@"storage size for float :%d",size(float));
    return 0;
}

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The void Types
       The void types specifies that no value is available. It is used in three kind of situations:

        1.Function returns as void
               There are various functions in objective-C which do not return value or you can say they return void. A function with no return value has the return type as void. For Example,
Void exit(int status);

        2.Function argument as void
               There are various functions in Objective-C which do not accept any parameter. A function with no parameter can accept as a void. For Example,
int rand(void);