• Variables enable the programmers to assign and manipulate data using symbolic names.
• Strings and numeric values can be stored in the memory of the computer for subsequent recall.
• Whenever the memory is used for this purpose the programmer must assign a unique name to each area in memory.
• In brief, a variable is a data name that may be used to store a data value, for easy retrieval.
  For example, the legal identifier names in ‘C++’ are,
• totsalary
• Counter
• Stdname

The maximum length of the variable is machine dependent. Usually 32 is the maximum number of characters permissible in a variable name.

Constants

• Constant is one that has a fixed value throughout the program.
• The constant can be viewed as a read only memory variable.
• In a program, the constant identifier should not be changed by any manifestation of the program statements.
• Constants are broadly classified into numeric constant and character constant.
• An integer constant is a sequence of digits that may or may not be prefixed with a minus sign.

  Some examples are,

• 14
• -32
• 0
• 576321
• Note that C++ does not support unary plus hence, +14 is not a valid integer.

  A real constant can be represented in 2 forms,

  1.Decimal form                 2.Exponent form
   Eg.12.75			Eg.1275E-2
  		               -14E-2
  A character constant is a single character enclosed within a pair of single quotes. 
      Eg.: ‘7’  , ‘M’
  

• Note that the character constant ‘7’ is not the same as the integer 7.
• A string constant is a group of characters enclosed double quotes. These characters may be letters, numbers, or any special characters.
• Eg.: “welcome” , “2000”

  
  Keywords and Identifiers << Previous
  Next >> Data Types

  Our aim is to provide information to the knowledge seekers. 

  
  
  comments powered by Disqus