The data type in C defines the amount of storage allocated to variables ,the values that they can accept ,and the operation that can be performed on variables.
C is called middle-level language because it is actually binding the gap between a machine level language and more conventional high-level languages. User can use c language to doSystem Programming (for writing operating system) as well as Application Programming (for generate menu driven customer billing system ). So that it is called middle level language.
Variables or symbolic variables are the names of storage location of computer memory whose values may vary during execution of a program.
Constant in C refers to the fixed values that do not change during the execution of a program. C supports several types of constants that I am discussing in this article.
C is one of the most popular computer language developed at AT&T’S Bell laboratories of USA in 1972 .It was developed by Dennis Ritchie.