General concepts - Data Types - Variables - Assignment

[Arthi Singaravelan]

   

Data types:  

•             Data types are just like initials.
  
•             Data types are the kind of data that the variable use in programming languages.
  
  
  
•              Generally the data types are classified as
  
  

                    i)int
                    ii)float
                    iii)char
                    iv)double.

•              The data type "int" holds 2 byte values, whereas "float" holds 4 bytes, and "char" data type holds 1 byte and "double" data type holds 8 bytes.
  
  
  
•               A particular variable can point to  a single data type throughout the program.
  
•               The concept of data type differs when we use a templates
  
•                When we use templates, a variable may point to a unknown data type. (i.e) a generic pointer.
  

Variables:

•               Variables are the memory location that the variable use in programming languages.
  
•                 A variable can be name of a person, or anything else.A user defined name can be defined to a variable.
  
• Rules for declaring a variables:
  
•                The variable must starts with an alphabet or an underscore i.e( _ ) followed by alphabets or numbers.
  
•                  No special characters except underscore should be used.
  
•                  The special words or reserved words i.e the keywords should not be used.
  
  

Syntax for a variable:

data_type variable_name;

Example:
int num;
float avg;
double area;
char name;

Declaring variable while using templates
template <class a>
class sample
{
   private:
   a ex;
   public:
     void fun()
     {
         cout<<"using templates";
     }
     void getdata()
     {
           cout<<"enter a integer value";
           cin>>ex;
           cout<<"enter a float value";
           cin>>ex;
           cout<<"enter a char value";
           cin>>ex;
      }
    The above program is implemented using templates.Here the variable "ex" is of generic type.(i.e) unknown data type.
    Hence it can take values for integer, or float, or character.

Assigning values:

    Values to a variable can be assigned in two ways:
          i) Direct assignment
          ii) Run time assignment

Direct assignment:
     Direct assignment to a variable is nothing but initialization of variables.
eg: int num=10;

Here the variable num takes the value 10 initially.Since it is a variable the value may be changed.

Run time assignment:

The values for the variables can be read from the user during the runtime.
(i.e) char name;
       cout<<"enter your name";
       cin>>name;