Memory Organization. Variables

Discuss how memory is organized

Variables correspond to storage locations in memory. They are denoted by identifiers, which obey the following restrictions:

• contain up to 31 characters;
• the first character must be a letter;
• names are case-insensitive (no distiction between upper and lower case).

At the beginning of the program, we declare the types of the variables. Declarations reserve the necessary number of bytes in memory and ``bind'' the variable name (identifier) to the address of the reserved memory space; the content of the reserved bytes will hold the variable's value. There are 6 intrinsic (default) data types in Fortran: character, logical, integer, real (single precision), double precision and complex. The last four types are refferred to as numeric data types.