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3. Use of pointer variables that facilitate two distinct kinds of uses - (a) they allow
indirect addressing (can be used to point to other data items), which is heavily
used in assembly language programming, and (b) they provide a method of
dynamic storage management (programmers can allocate a piece of dynamic
storage and set a pointer to its address).
4. Addition of new control statements to facilitate easier programming. These
include CASE statement for multiple options selection, EXIT statement for
prematurely departing from a loop, and CYCLE statement for transferring control
to the bottom of a loop but not out.
As FORTRAN language is oriented towards solving problems of a mathematical
nature, it has been designed as an algebra-based programming language. Any
formula or mathematical relationships that can be expressed algebraically can
easily be expressed as a FORTRAN instruction, for example, A = B + C - D. To
illustrate the nature of FORTRAN programs, a simple FORTRAN program to
compute and print the sum of 10 numbers is given in Figure 12.16.
FORTRAN PROGRAM TO COMPUTE
THE SUM OF 10 NUMBERS
SUM = 0
DO 50 I =1,10
READ (5, 10) N
SUM = SUM + N
WRITE (6, 20) SUM
10 FORMAT (F6.2)
20 FORMAT (IX, 'THE SUM OF GIVEN NUMBERS = ', F10.2)
END It can be seen from the example of Figure 12.16 that a FORTRAN program
consists of a series of statements for input/output, calculation, logic/comparison,
etc. The words READ, WRITE, DO, CONTINUE, STOP, END, etc. in the
statements mean exactly what one would expect.
In the given example, the first two lines that begin with the character C are
comment statements. Comment statements are used in programs for the purpose of
documentation or explanation designed to assist anyone reading the source
program listings. Comments do not form a part of the program logic and are
ignored by the computer. In the third statement of the program, the value of SUM
is initialized to zero. The next statement starts a DO loop. This loop ends in the
line having label 50, wh...
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This document was uploaded on 04/07/2014.
- Spring '14